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Easy Water Temperature Science Experiment + Video & Lab Kit

Can you see thermal energy? Yes, with just a few common kitchen items!

Although we can explain that molecules move faster when hot and slower when cold, in this science experiment kids will be able to see thermal energy in action and explore the concept hands-on.

We’ve included a materials list, printable instructions, and a simple explanation of how the experiment works. Enjoy our demonstration video to get started!

JUMP TO SECTION: Instructions | Video Tutorial | How it Works

Supplies Needed

• 3 Glass Jars
• Room Temperature Water
• Food Coloring

Water Temperature Science Lab Kit – Only $5

Use our easy Water Temperature Science Lab Kit to grab your students’ attention without the stress of planning!

It’s everything you need to  make science easy for teachers and fun for students  — using inexpensive materials you probably already have in your storage closet!

Water Temperature Science Experiment Instructions

Step 1 – Begin by preparing three identical jars of water. Fill one jar with cold water, one jar with room temperature water, and one jar with hot water.

Helpful Tip: For cold water, fill the jar and put it in the fridge for an hour or two. For the room temperature water, fill the jar and leave it on the counter for an hour or two. For the hot water, boil the water on the stove or put it in the microwave for a minute or two.

Before moving to the next step, take a moment to observe the jars. The temperature of water should be the only difference. Do you think the water temperature will impact what happens when the food coloring is added to each jar? Write down your hypothesis (prediction) and then continue the experiment to see if you were correct.

Step 2 – Place 2-3 drops of food coloring in each jar and observe what happens.

You’ll notice right away that the food coloring behaves differently in each jar. Was your hypothesis correct? Do you know why the food coloring slowly mixed with the cold water and quickly mixed with the hot water? Read the how does this experiment work section before to find out the answer. 

Video Tutorial

How Does The Experiment Work?

When observing the food coloring in the water, you will immediately notice that it behaves differently based on the temperature of the water.

Even though the glasses of water look the same, the difference in the water temperature causes the molecules that make up the water to behave differently. Molecules that make up matter move faster when they are warmer because they have more thermal energy and slower when they are colder because they have less thermal energy. In this experiment, the molecules in the hot water are moving around much faster than the molecules in the cold water.

Thermal Energy is the total energy of the particles in an object.

When placed into water, food coloring will begin to mix with the water. The food coloring will mix the fastest in the hot water because the molecules are moving fast due to their increased thermal energy. These fast-moving molecules are pushing the molecules of food coloring around as they move, causing the food coloring to spread faster.

The food coloring in the room temperature water will take longer to mix with the water because the molecules are moving more slowly due to their decreased thermal energy.

Lastly, the food coloring in the cold water will take a long time to mix with the water because the molecules are moving even slower due to a further decrease in thermal energy.

More Science Fun

Eventually, the food coloring will mix throughout all of the jars. Expand on the experiment, by estimating how long it will take to mix with the water in each jar. Then set a timer and find out how close your estimate was.

In addition, you can also try these other fun experiments using water and food coloring:

• Walking Water Science Experiment – Can water walk upwards against gravity? No, not really, but what makes water seem like it defies gravity is what we’re going to explore in this easy science experiment.
• Color Changing Walking Water Science Experiment   – Much like the regular walking water science experiment, but with an added “colorful” twist.
• Coloring Changing Water Science Experiment – Science or magic? Try this experiment at home with your kids and watch their eyes light up as you pour the liquid into the bowl and “create” a new color.

Water Temperature Experiment

• Three Glass Jars

Instructions

• Begin by preparing three jars of water. Fill one with cold water, one with room temperature water, and one with hot water. Helpful Tip: For cold water, fill the jar and put it in the fridge for an hour or two. For the room temperature water, fill the jar and leave it on the counter for an hour or two. For the hot water, boil the water on the stove or put it in the microwave for a minute or two.
• Place 2-3 drops of food coloring in each jar.
• Observe what happens to the food coloring. Does it behave differently in each jar?

Reader Interactions

May 5, 2017 at 1:17 pm

thank you for u showing my kids this they love it.

March 30, 2019 at 11:58 pm

You’re amazing!!!!

April 7, 2022 at 10:35 am

I like it a lot it’s so cool that I did it for my class and got a A+

March 9, 2022 at 6:10 pm

I will be using this at Parent Science Night tomorrow!

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Hot and Cold Water Density Experiment

July 20, 2022 By Emma Vanstone Leave a Comment

This easy science activity demonstrates the difference in density between hot and cold water. It can be a bit messy so I would either do it outside or put the jars in a tray.

The demonstration works as cold water is more dense than hot water so the hot water sits on top of the cold.

When water is heated, water molecules move around faster, bounce off each other and move further apart. As there’s more space between the water molecules the density of warmer water is less than the same volume of cooler water.

You’ll need

Two small or medium glass jars

Small sheet of card

Food colouring

Tray – optional but advised

How to make hot and cold water density jars

Fill one of the jars with hot water and add a couple of drops of red food colouring.

Fill the second jar with cold water and add a drop of blue food colouring.

Check both jars are as full as possible.

Hot water on top of cold

Place a sheet of card over the jar filled with hot water and carefully place it on top of the jar with the cold water.

When the jars are balanced, carefully remove the card.

The two colours of water should remain separate.

Cold water on top of hot

Refill the jars and try again. This time place the cold water on top of the hot water.

The two colours of water should mix.

Density of water

Warm water is less dense than cold water so the red warm water sits on top of the cold water when the card is removed from between the jars.

If you put the hot water on the bottom the colours mix as the denser cold water drops down into the less dense hot water.

Our photo isn’t perfect as it’s hard to remove the card between the jars without some water spilling out, but do send me a photo if you get a better result.

Another density demonstration can be done using salt to increase the density of one jar of water. In the image below the blue water has the salt added.

Safety Notice

Science Sparks ( Wild Sparks Enterprises Ltd ) are not liable for the actions of activity of any person who uses the information in this resource or in any of the suggested further resources. Science Sparks assume no liability with regard to injuries or damage to property that may occur as a result of using the information and carrying out the practical activities contained in this resource or in any of the suggested further resources.

These activities are designed to be carried out by children working with a parent, guardian or other appropriate adult. The adult involved is fully responsible for ensuring that the activities are carried out safely.

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How to Do the Hot and Cold Water Density Experiment

Categories Science Experiments

One of my favorite things to do are STEM activities and ocean science experiments ! I love seeing the reaction on a child’s face when they see science work before their eyes.

A lot of science experiments take a long time, but not the hot and cold water density experiment !

In this temperature density experiment, kids will experience water density, color mixing, molecule science, and a whole lot more with just one experiment that takes less than 10 minutes to complete.

Try it out at home or in the classroom!

Hot and Cold Water Density Experiment

If you love doing quick science experiments that wow, try this amazing hot and cold water experiment.

Kids will ask to do this one over and over again!

Why STEM Activities are Important for Kids

Today, science experiments for kids are more important than ever. Science and technology are huge parts of our world today, and the future will be even more science and tech-focused.

Kids who aren’t immersed in the world of science and STEM exploration from a young age will be left behind their peers, and may struggle to find work in the fast-changing landscape of future careers.

Science experiments are usually basic, but they can help spark a love of science and discovery in a child that will follow them throughout their life.

The simple science experiment that a child does today may spark their desire to discover something that will change the world in the future.

Every day, young children are using science experiments to solve real-world problems in medicine and technology that have never been uncovered before.

And all these scientific discoveries start with a firm foundation in science and STEM.

The Scientific Method for Kids

Every science experiment contains four elements:

Kids should start every science experiment with a question, even if that question is just “what will happen?”

A Hypothesis

Before doing any experiment, children should record what they believe will happen.

An Experiment

This is where the fun part comes into play. Test the hypothesis to determine if it answers the question fully.

A Recording and Analysis

As the test is completed, record what happened and analyze why.

Try different variables and try a new test to see if the original answer is confirmed or disproved.

Water Density Experiment Explanation

Here is the hot and cold water density experiment explanation.

The hot and cold water science experiment works because of the different density of hot and cold water.

Certain liquids are less dense than others. If you’ve ever made a density jar, it’s easy to see this in action.

But… water has the same density as other water, right? So why does it stay separated?

The secret is in the temperature of the water.

The molecules in hot water move faster than those in cold water. Hot water molecules bounce around and leave gaps. This makes hot water slightly less dense than cold water.

So when you put the cold water on the bottom, the denser cold water stays there.

But when you put the cold water on the top, heat molecules rise. So the colors mix right away.

Because you’re mixing primary colors, they mix into secondary colors when the hot water is on the bottom.

Supplies for the Temperature Density Experimemnt

Here are some essential supplies for the hot and cold water density experiment.

• Food coloring
• Cardstock paper

Our Favorite Water Science Kits

Here are some of our favorite water science kits that you can turn into ice science too!

• Water science kit for early elementary
• Water filtration science experiment
• Air and water power science kit
• Clean water science kit
• Water rocket kit

Water Density Experiment Set-Up

Before starting this experiment, you’ll need to laminate a small card slightly larger than the mouth of your mason jar.

Boil a pot of hot water and fill a large pitcher with ice water.

Fill three jars all the way to the top with ice water.

Fill three more jars up to the top with hot water (but don’t make it so hot that you can’t touch the sides of the jar).

Dye one cold jar yellow, one blue, and one red. Repeat for the hot jars.

More Water Experiments for Kids

• How to Make Water Slime that Looks Just Like Fresh Water!
• Fortnite Slurp Drink Water Density Experiment
• How to Make an Instant Ice Tower
• Milk jug water wheel

How to Do the Water Density Experiment

Learn how hot and cold water have different densities with this hands-on, colorful, and fun water science experiment! It's the perfect "wow" science experiment that gets strong reactions every time!

• Plastic mason jars

Instructions

First, do the experiment with the cold water on the bottom.

• Place the index card over the mouth of the hot water jar. Press slightly to make a seal.
• Flip the jar over and place it on top of the cold water jar (make sure it's a color combo that will make a secondary color).
• Line up the lip of the jars and carefully pull the card out. The water will stay separated!
• Repeat for the other four jars.
• Carefully grip the center of the jars and flip them. They will mix into secondary colors right away!
• Because cold water is denser than hot water, the colors do not mix until gravity pulls the cold water down into the hot water.

If you don't want the mess risk of flipping the jars, you can simply put the hot water jar on the top and use the index card over the cold water. Then, when you move the card out of the way the colors will mix and you won't have to flip any jars.

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Balloon In Hot and Cold Water – Experiment

• March 30, 2021
• 7-9 Year Olds , Household Items , Physics

Let’s discuss about ‘Balloon in hot and cold water experiment’ in this article. This interesting balloon experiment helps children to learn about density , surface tension , and air pressure .

Balloon in hot and cold water experiment

• The volume of air changes based on the temperature surrounding it.
• Air expands or contracts based on increase or decrease in surrounding temperature.

Things you need to do Balloon Experiment

1) Two plastic/ glass container (bottles)

2) Balloons

3) Hot Water

4) Ice cubes as a cold water source

5) Containers to place hot and cold water

Preparation Steps

1) You can prepare your children or students by asking “How can you inflate the Balloon without touching it?”.

2) Note down their expected answers. But discuss their solutions only after performing the experiment to catch the science concepts behind it easily.

Step by Step Directions

Let’s start with the hot air experiment.

Step-1: 

Take a glass container and add cold water. Then, add few ice cubes to it to keep it cold.

Step-2: 

Pick another glass container and add some amount of hot water into it. Ensure the hot water’s hotness need not to be sizzling.

As step 3, bring our Balloon over the neck or mouth of the crystal clear plastic bottle in an upside-down position. And fix the mouth of the Balloon to the mouth of the bottle as shown in the picture.

Make sure the bottle is empty before you attach the Balloon to it.

Repeat the same method and prepare another set of water bottle and Balloon using the other empty bottle.

In this step, keep the ballon attached bottle inside the container, which consists of hot water. Let the bottle sit in hot water for some time.

You will observe the Balloon starts inflating itself without any external force. Amazing, isn’t it!?

Step-5: 

And then bring the same and another set of water bottle into the container which consists of cold water. And allow it to sit for some time to see the results.

You will observe the Balloon starts shrinking itself by deflating the air inside it.

Note:  If you feel the hot water is becoming cool, replace it with another hot water cup. In the same way, if you feel the cold water is becoming hot due to outside temperature impact, add some more ice cubes and make it cool. In this way, you can maintain the temperatures of the water while repeating the experiments.

Science Behind Expanding Balloon on Hot Water

The quantity of air occupied in a particular space, i.e., an open or closed container, denotes ‘Volume.’ 

Well, an empty water bottle is also populated with a certain amount of air molecules inside it—the air molecules inside and outside the bottle move with equal pressures at normal surrounding conditions.

In this activity, when we attach a balloon over the bottle’s mouth and place it in a hot water container, the Balloon starts inflating. It is because the hot air molecules enter into the Balloon from the bottle, which is in a hot water container.

These hot air molecules move faster inside the Balloon and occupy more space as they become less dense than usual. When they become less dense, it requires more space to settle, and that is why the Balloon starts inflating to provide more space for hot air molecules.

And when the Balloon inflates in hot water, bring it into the container containing cold water. Here, the cold air molecules replace the hot air molecules because hot air molecules cool down due to cold water.

When the air molecules become colder, air molecules’ density gets back to a denser state and requires less space to occupy. That is why the inflated Balloon deflates when the bottle is placed inside a cold water container.

This is how the volume of air calculated:

Volume= Mass x Density

Safety Tips

Have adult supervision at all times during the experiment to avoid any unforeseen incidents.

Suggested to wear gloves and safety glasses while doing experiments with hot water.

Avoid handling hot water by small kids.

Learning for Elementary, Middle School, and High School Students

The same experiment can be used differently based on the level /grade of the students.

Elementary Students

When kids are in elementary school, it is the best time to learn about different states of matter, i.e., solids, liquids, and gases. Solids and liquids are visible to the naked eye, and hence students can easily catch up with the properties and characteristics. And it is easy for them to compare various objects and liquid things and determine the state of matter properties.

But when coming to gases, it is difficult for them to determine their properties because gases won’t appear to the naked eye, and children go confused. That is why we need to explain them clearly by concentrating much on performing various science experiments that involve gases. One such experiment is the ‘Balloon in a bottle’ experiment.

Through this experiment, students can quickly learn about gases and their properties.

Middle School Students

In middle school, students focus on macroscopic particles and determine the objects around them and tell whether they have solid or liquid or gaseous properties. Because at this level, they will get to learn about states of matter in regards to their arrangement, position, and movement. Also, they can explore that all forms of matter are made of atoms and molecules that consist of weight, especially gases. As the air is invisible, they think that gases do not have mass, but they learn about gases containing mass with this experiment.

Besides, they can explain the conservation of matter with a good reason using the concept of closed systems.

High School Students

At this level, as the name suggests, students become sharp and can apply their knowledge on gases. This knowledge helps in understanding even the difficult context of gases, i.e., ‘Gas Laws.’ Also, they can apply Charles Law and explain Gas Law. And using conservation of matter principles and laws, they will make out the differences in temperatures and their relation to the volume of gas.

In this way, students at different school grades learn the gaseous properties by performing this super classic experiment of ‘Balloon in a Bottle.’

Laws Behind the Experiment

Gas Law or Gas Laws is/are a collection of laws which include Boyle’s Law, Charles’s Law, Gay-Lussac’s Law, Ideal Gas Law, and Avogadro’s Law. These laws combine to state how an amount of gas reacts to changes in temperature, pressure, and temperature. The following are such statements these combined laws work on:

1) The complete temperature of a gas

2) The amount of volume working with a gas

3) The amount of pressure experienced between the walls of a container and a gas

4) The mass of a gas

The above-mentioned combination laws were a great invention during the 18th century, and here are the definitions of each law:

    Boyle’s Law:  The law which states the kith and kin between the volume and pressure of a given amount of gas is nothing but Boyle’s Law.

    Charles’s Law:  Charles’s Law is the law that tells about the absolute temperature of a gas and its association with the volume employed by it. 

    Avogadro’s Law:  The type of law which states the correlation between the number of moles of a gas and the amount of volume occupied by it refers to Avogadro’s Law. 

    Gay-Lussac’s Law:  Gay-Lussac’s Law tells that the relation between the absolute temperature and its pressure is directly proportional at constant volume. 

    Ideal Gas Law:  Ideal gas law is a combination of three laws, i.e., Boyle’s Law, Charles’s Law, Avogadro’s Law, and hence refers to the term ‘combined gas law.’ This law states the differential behavior of gases at different conditions and concludes that a gas’s pressure is directly proportional to the absolute temperature. 

Pressure, volume, and temperature are the three significant physical factors that determine the behavior of gases. When these parameters are at standard conditions, the activities of all types of gases remain the same. The states of gases can vary based on the condition. 

So, the gas law and all other five laws state all gases’ behavior is associating with all three physical parameters.

Boyle’s Law Formula: P∝1/V

Charles’s Law Formula: V∝T

Avogadro’s Law Formula: V ∝ n

Ideal Gas Law Formula: PV= nRT

Gay-Lussac’s Law Formula: P ∝ T

Here, P= Pressure of the gas, V= Volume of the gas, T= Absolute Temperature of a gas, n= Number of moles, R= Equilibrium Constant.

Here are some worksheets that would complement the science experiment. Attempting these worksheets might help studnets to sustain the knowledge gained through the experiment. On the other hand, teachers use these worksheets to understand and monitor student’s previous and current knowledge.

https://scied.ucar.edu/sites/default/files/files/activity_files/BalloonOnBottle_0.pdf

https://www.flinnsci.com/api/library/Download/e2dfff9fc2324f51889429583a51ac63

https://ps21pd.weebly.com/uploads/1/2/0/6/12065719/kinetic_theory_-_hot_and_cold_balloons.pdf

https://www.sciencenorth.ca/sites/default/files/2020/June%202%20Grade%207%20Particle%20Theory%20Offline%20ENG.pdf

Practical Applications

Let’s learn how to apply these science concepts in real life applications happening around us.

Hot air balloon:  Yes, the science behind hot air balloon and Balloon in the bottle activities is similar, i.e., hot air rises, sending the cool air to replace the space created by it. When you provide heat flames in the hot air balloon set up, the heat energy enters into the Balloon.

Generally, the hot air consists of less dense air molecules, which tend to rise. That’s why and the hot air balloon rises in the sky until they provide enough heat.

Not only air, any substance that exhibits less dense molecules than the surrounding gaseous or liquid matters float . Forex: Wood floats on top of the water because wood consists of less dense molecules than water. This phenomenon of increasing the molecules’ speed regarding the increase in temperature of a gas refers to ‘Thermal Expansion.’ And the wonder of floating objects due to the pressure or force exerted is ‘Buoyancy.’

Sun Producing Wind on Earth:  The winds produced by Sun on the Earth also exhibit the same phenomenon, i.e., thermal expansion and buoyancy.

Earth’s temperature is uncertain, so we cannot predict its long-term weather and climatic conditions. It is because different parts of Earth receive heat from Sunlight at different times as Earth is round and rotating.

So, the Sun can’t provide Sunlight to all parts of the Earth at the same time. Hence, Earth receives different air temperatures at places closer to the surface of the Earth. Besides, the Sun’s angle is focussing its Sunlight on the Earth also plays a significant role in changing the temperatures of Earth.

According to the above concepts, several continents on Earth receive more heat than other continents. Comparing land and water, land absorbs more heat faster than water, and therefore we see continents with more land exhibits high temperatures.

But during nights land releases heat more quickly than air and hence we feel cooler climates at night time. In this way, Earth reveals different climatic conditions and atmospheric temperatures during the day and night times.

Let us discuss these concepts in detail with a practical example, i.e., Off-shore and On-shore Winds. During nights, the oceans’ surface gets warmer so quickly because the surrounding land cools down and shows lesser temperatures.

As a result, the warmer air becomes less dense and rises upwards, leaving the space on the surface occupied by the cold air from the land. Thus, creating the off-shore winds that produce renewable and pure energy.

And at daytime, we experience on-shore winds that mean the land absorbs more heat from the Sun and exhibits warmer air. This hot air does not remain on the land surface; instead, it rises into the air because it consists of less dense air molecules.

Simultaneously, the temperature at the ocean level exhibits less heat than the land surface temperature. So, the cold air from the ocean surface replaces the hot air molecules’ space creating on-shore winds.

Lesson Plan

Here is the best lesson plan on the ‘Balloon in hot and cold water’ experiment.

Preparations

1) Ask the students whether they can inflate the Balloon without touching it. Note down their answers and discuss their solutions after the experiment.

2) First, invite your student’s answers and discuss their solutions with a scientific reason.

3) You can encourage and inspire students by telling them that they are upcoming engineers, chemists, and other respectable designations. Forex: if a student predicts the answer would be ‘by adding baking soda and vinegar,’ explain why his response went wrong. Then, encourage him by saying he/she is thinking smartly like a chemist. In this way, depending on their predictions, a teacher can inspire them with specific designations.  

4) If a student does not respond to your challenge of inflating a balloon without touching it, then give him an example and ask him/her to compare. Let the student come up with his/her answer with a bit of explanation.

Guide your students on the instructions of the ‘Balloon in hot and cold water’ experiment step by step, clearly as mentioned at the top of this post. You can also ask and discuss a few questions related to the subject while experimenting. Such that students feel more encouraged and involved in the topic rather than feeling bored.

Here are the basic questions you can discuss with students:

1) Why does the Balloon inflated on itself?

2) What is the difference between hot and cold water changes and their impact on the Balloon?

3) How long the Balloon takes time to inflate itself in hot water?

Explain about Misconceptions

Students think that hot air blows up the Balloon as the hot air rises upwards. But prove it as a misconception by reversing the bottle with an inflated balloon. Still, the Balloon remains inflated without deflating. It is because hot air rises when there is cold air beside it.

Finally, explain the background science involved in this experiment and discuss students’ predicted answers with a scientific reason. Tell them clearly that their answers may not apply in this science activity, but they may use them in another way of experimenting.

In hot water, the Balloon inflated because of hot air molecules, and in cold water, the Balloon deflated because of cold air molecules. The hot air molecules are less dense in weight and tend to rise and occupy more space. That’s the reason the hot air molecules travel inside the Balloon and make it expand. In contrast, the cold air molecules are denser in weight and require less space, causing the Balloon to deflate.

Take an empty plastic water bottle. Attach a balloon (make sure it is not leaking anywhere on its surface) to the bottle’s mouth using its neck part by placing it upside down. That means the mouth of the Balloon and the bottle gets attached in opposite directions using their mouthparts. Now place the bottle set up in a container that consists of hot water in it. Leave it for some time. The Balloon starts inflating by filling its inside part with hot air molecules.

Bring the Balloon’s mouth part in an upside-down position over the neck part of the bottle. And then stretch the Balloon’s opening around the neck part of the bottle. But before that, you need to uncap the bottle. That’s it! Your Balloon’s opening nicely sits over the bottleneck part.

Boyle’s Law is valid at very high temperatures until or unless the gas remains as a gaseous matter. Because at high temperatures, the gases may change their state of mass, for which Boyle’s law is not applicable. Boyle’s law tells that the volume and pressure of a gas-related each other quite the opposite.

When you squeeze the bottle, the Balloon begins inflating itself because we squeeze some air molecules into it while squeezing the bottle. And due to more air occupying inside the Balloon, the Balloon starts expanding and inflates itself to fit the air molecules coming inside. When you stop squeezing the bottle, the balloon deflates.

When you let the Balloon warm up again, it starts inflating itself because of warmer air molecules. The warmer air molecules rise and enter into the Balloon, making it expand. Hot air molecules are less dense in weight and tend to travel upwards. And they require more space since they like to scatter in larger areas.

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Learn about Hot and Cold Temperature: Easy Science Experiments for Kids

Teach kids about temperature as they perform easy science experiments with hot and cold water and the our free printable.Thank you for visiting. This post…

Teach kids about temperature as they perform easy science experiments with hot and cold water and the our free printable.

Thank you for visiting. This post may contain affiliate links to recommended products at no extra cost to you. Read our Disclosures and Terms of Use . Don't miss out again, become a  Reader here <--it's FREE. 

We did 6 different science activities to learn about temperature and the difference between hot and cold. We have a free printable activity to go along with all the hands-on activities so your little scientists can have fun understanding temperature while learning more about the world around them. Each of the activities are super simple to set up, mainly because most of the supplies come straight from your kitchen faucet.

I loved watching my kids try out these science experiments. They were so eager to check everything out and best of all their understanding of temperature grew. I think that my favorite activity was watching the food coloring disperse in hot and cold water–such a simple activity and yet so pretty to watch! If you enjoy watching your kids do science as much as I do, check out this free homeschool science curriculum . 

More Science Experiments:

• Grow a Rainbow Science Experiment
• Snowflake Symmetry Activity
• How to Make Crystal Balls

Learn about Hot and Cold Temperature Science Experiments

BECAUSE ALL ACTIVITIES ARE BETTER WITH A BOOK!

Click photos: Affiliate links to more information on these books we love!

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• Voss Water bottle (or plastic bottle)
• Red and blue food coloring
• Thermometer (We used a candy thermometer)
• Water balloons
• Ice Cube tray
• Glass measuring cups

DIRECTIONS:

Frozen Water

Fill containers half full with water. Mark the water line with a marker or I used a rubber band because we use our water bottles a lot. Put them in the freezer until they are completely frozen. Have children look at the new water lever (ice level). The frozen line should be above the water line because when water freezes it expands because the hydrogen bonds in the water that form are more spread out then when it is in liquid state.

Red and Blue Food Coloring Race

Fill one tall container with ice cold water and another tall container with hot water (not boiling). Have child drop a few drops of red food coloring in the hot bottle and blue food coloring in the cold water and watch (this experiment is very fast so don’t look away). Technically you could use whatever color food coloring you have but since red and blue help to reinforce the difference in temperatures we used those colors. The blue food coloring should move slower through the water compared to the red food coloring because the water molecules in the hot water have more energy and move faster then the water molecules in the cold water.

Blue Ice Melt

Fill a pitcher with water and add drops of blue food coloring. Fill an ice tray with the blue water and put it in the freezer until the ice is solid. Fill a container with room temperature water and place the blue ice inside. The ice should float and the blue water that melts from the ice cube should sink. This is because cold water (and air) is more dense compared to regular temperature water and will sink in warmer water. They may have heard before that hot air rises and cold air sinks, now they can visualize it.

Hot & Cold Balloons

Fill small balloons with some air. We used water balloons. Make them relatively the same size. Place one in cold water and one in hot water. We used a pink balloon for the hot water and the blue balloon for the cold water. The hot water balloon should get larger as the air expands as it gets warm and the cold water balloon should shrink as the air inside condenses.

Thermometer Reading

After the balloon test we used our thermometer to measure the water temperatures and then we wrote the temperature on our Hot and Cold Molucule Craft (See below).

Hot and Cold Molecule Craft (Available to download for free below)

Have children glue molecules in the hot and cold cups showing their understanding of hot and cold. The hot molecules should be spread out and moving around while the cold molecules should be condensed and slow moving.

DOWNLOAD THE PRINTABLE HERE:

Print the directions here:.

Hot and Cold Temperature Science Experiments

• Thermometer

Instructions

• Frozen Water Fill containers half full with water. Mark the water line with a marker or I used a rubber band because we use our water bottles a lot. Put them in the freezer until they are completely frozen. Have children look at the new water lever (ice level). The frozen line should be above the water line because when water freezes it expands because the hydrogen bonds in the water that form are more spread out then when it is in liquid state. Red and Blue Food Coloring Race Fill one tall container with ice cold water and another tall container with hot water (not boiling). Have child drop a few drops of red food coloring in the hot bottle and blue food coloring in the cold water and watch (this experiment is very fast so don't look away). Technically you could use whatever color food coloring you have but since red and blue help to reinforce the difference in temperatures we used those colors. The blue food coloring should move slower through the water compared to the red food coloring because the water molecules in the hot water have more energy and move faster then the water molecules in the cold water. Blue Ice Melt Fill a pitcher with water and add drops of blue food coloring. Fill an ice tray with the blue water and put it in the freezer until the ice is solid. Fill a container with room temperature water and place the blue ice inside. The ice should float and the blue water that melts from the ice cube should sink. This is because cold water (and air) is more dense compared to regular temperature water and will sink in warmer water. They may have heard before that hot air rises and cold air sinks, now they can visualize it. Hot & Cold Balloons Fill small balloons with some air. We used water balloons. Make them relatively the same size. Place one in cold water and one in hot water. We used a pink balloon for the hot water and the blue balloon for the cold water. The hot water balloon should get larger as the air expands as it gets warm and the cold water balloon should shrink as the air inside condenses. Thermometer Reading After the balloon test we used our thermometer to measure the water temperatures and then we wrote the temperature on our Hot and Cold Molucule Craft Hot and Cold Molecule Craft Have children glue molecules in the hot and cold cups showing their understanding of hot and cold. The hot molecules should be spread out and moving around while the cold molecules should be condensed and slow moving. We used marshmallows. Available here: https://alittlepinchofperfect.com/learn-hot-cold-temperature-science-experiments-kids/

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Home » Articles » STEM » STEM Science » How to Demonstrate Diffusion with Hot and Cold Water

How to Demonstrate Diffusion with Hot and Cold Water

We all need some space sometimes, right that’s true down to a molecular level. molecules don’t like to stay too close together and will try to move to less crowded areas. that process is called diffusion and we will explore all about it in this simple but revealing experiment., article contents.

What is Diffusion?

Have you ever smelled your neighbor’s lunch on your way home? Or smelled someone’s perfume minutes after that person was gone? You experienced the diffusion!

Diffusion is a movement of particles from the area of high concentration to an area of low concentration. It usually occurs in liquids and gases.

Let’s get some complex-sounding terminology out of the way. When talking about diffusion, we often hear something about the concentration gradient (or electrical gradient if looking at electrons). Gradient just means a change in the quantity of a variable over some distance. In the case of concentration gradient, a variable that changes is the concentration of a substance. So we can define the concentration gradient as space over which the concentration of our substance changes.

For example, think of the situation when we spray the air freshener in the room. There is one spot where the concentration of our substance is very high (where we sprayed it initially) and in the rest of the room it is very low (nothing initially). Slowly concentration gradient is diffusing – our freshener is moving through the air. When the concentration gradient is diffused, we reach equilibrium – the state at which a substance is equally distributed throughout a space.

It’s important to note that particles never stop moving , even after the equilibrium is reached. Imagine two parts of the room divided by a line. It may seem like nothing is happening, but particles from both sides are moving back and forth. It’s just that it is an equal probability of them moving from left to right as it’s from right to left. So we can’t notice any net change.

Diffusion is a type of passive transport . That means it doesn’t require energy to start. It happens naturally, without any shaking or stirring.

There is also a facilitated diffusion which happens in the cell membranes when molecules are transported with the help of the proteins.

You may remember hearing about Osmosis and think about how is this different from it. It is actually a very similar concept. Osmosis is just a diffusion through the partially permeable membrane. We talked about it more in our Gummy Bear Osmosis Experiment so definitely check it out.

What causes Diffusion?

Do particles really want to move somewhere less crowded? Well, no, not in the way we would think of it. There is no planning around, just the probability.

All fluids are bound to the same physical laws – studied by Fluid mechanics , part of the physics. We usually think of fluids as liquids, but in fact, air and other types of gas are also fluids ! By definition , fluid is a substance that has no fixed shape and yields easily to external pressure.

Another property of the fluids is that they flow or move around. Molecules in fluids move around randomly and that causes collisions between them and makes them bounce off in different directions.

This random motion of particles in a fluid is called Brownian motion . It was named by the biologist Robert Brown who observed and described the phenomenon in 1827. While doing some experiments with pollen under the microscope, he noticed it wiggles in the water. He concluded that pollen must be alive. Even though his theory was far off, his observation was important in proving the existence of atoms and molecules.

Factors that influence Diffusion

There are several factors that influence the speed of diffusion. The first is the extent of the concentration gradient . The bigger the difference in concentration over the gradient, the faster diffusion occurs.

Another important factor is the distance over which our particles are moving. We can look at it as the size of a container. As you may imagine, with the bigger distance, diffusion is slower, since particles need to move further.

Then we have characteristics of the solvent and substance. The most notable is the mass of the substance and density of the solvent . Heavier molecules move more slowly; therefore, they diffuse more slowly. And it’s a similar case with the density of the solvent. As density increases, the rate of diffusion decreases. It’s harder to move through the denser solvent, therefore our molecules slow down.

And the last factor we will discuss is the temperature . Both heating and cooling change the kinetic energy of the particles in our substance. In the case of heating, we are increasing the kinetic energy of our particles and that makes them move a lot quicker. So the higher the temperature, the higher the diffusion rate.

We will demonstrate the diffusion of food coloring in water and observe how it’s affected by the difference in temperature. Onwards to the experiment!

Materials needed for demonstrating Diffusion

• 2 transparent glasses – Common clear glasses will do the trick. You probably have more than needed around the house. We need one for warm water and one for cold water so we can observe the difference in diffusion.
• Hot and cold water – The bigger the difference in temperature in two glasses, the bigger difference in diffusion will be observed. You can heat the water to near boiling or boiling state and use it as hot water. Use regular water from the pipe as “cold water”. That is enough difference to observe the effects of temperature on diffusion.
• Food coloring – Regular food coloring or some other colors like tempera (poster paint) will do the trick. Color is required to observe the diffusion in our solvent (water). To make it more fun, you can use 2 different colors. Like red for hot and blue for cold.

Instructions for demonstrating diffusion

We have a video on how to demonstrate diffusion at the start of the article so you can check it out if you prefer a video guide more. Or continue reading instructions below if you prefer step by step text guide.

• Take 2 transparent glasses and fill them with the water . In one glass, pour the cold water and in the other hot water. As we mentioned, near-boiling water for hot and regular temperature water from the pipe will be good to demonstrate the diffusion.
• Drop a few drops of food coloring in each cup . 3-4 drops are enough and you should not put too much food color. If you put too much, the concentration of food color will be too large and it will defuse too fast in both glasses. 
• Watch closely how the color spreads . You will notice how color diffuses faster in hot water. It will take longer to diffuse if there is more water, less food color and if the water is cooler.

What will you develop and learn

• What is diffusion and how it relates to osmosis
• Factors that influence diffusion
• What is Brownian motion
• How to conduct a science experiment
• That science is fun! 😊

If you liked this activity and are interested in more simple fun experiments, we recommend exploring all about the heat conduction . For more cool visuals made by chemistry, check out Lava lamp and Milk polarity experiment . And if you, like us, find the water fascinating, definitely read our article about many interesting properties of water .

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Hot and Cold Water Science EXPERIMENT

Are you looking for a science experiment to do with your kids at home? Then, wow your preschoolers or kindergarteners with a science experiment that teaches them how the density of water changes when it is heated. After all, who doesn’t enjoy science activities for kindergarten that only require common household items?

SUPPLIES FOR THE WATER SCIENCE EXPERIMENT

You will need an adult to supervise this activity as it involves hot water.

• Two identical wide mouthed small clear glass jars
• Food Coloring – Red and Blue
• Index or plastic card ( Old playing card can be used if it covers the mouth of the jar )
• Shallow Dish/Plate or baking pan
• Hot and Cold Water

How do you do hot and cold water density experiment?

Fill one jar with cold water and the other with hot water.

Pour blue food coloring into the cold water and red food coloring into the hot water.

Make sure both jars are completely filled with water. To avoid spills, place them in the shallow plate.

Tap the card gently on top of the hot water jar. The card should completely cover the jar’s mouth. It will aid in the formation of a seal between the water and the jar.

Pick up the hot water jar with care (you’ll need an adult for this part) and turn it completely upside-down.

If the jar is tilted but not completely turned over, the water will gush out and make a mess. So, without hesitation, flip the jar over.

You may not need to place your hand on the card because the vacuum created inside the jar keeps it on the surface.

Before attempting it with hot water, it is best to practice turning the jar upside down with an index card placed on top of it under the sink using tap water.

Place the red jar upside down on top of the blue jar. Check that the edges of both jars are perfectly aligned all around.

Allow someone to hold both jars while you slowly and patiently pull out the card from between the jars.

RELATED POST : HOW DOES WATER WORK AS A MAGNIFYING GLASS

DENSITY EXPERIMENT : THE SCIENCE OF Hot and Cold Water

Why does hot and cold water not mix?

Empty and clean both jars. Carry out the previous experiment, but this time turn the blue jar upside down and place it on top of the red jar. What happens next? Why does the water mix this time?

The reason for this is that when two liquids of different densities are combined, the liquid with lower density floats on top of the denser liquid.

Hot water has a lower density than cold water.

When water is heated, the water molecules begin to bounce off each other, causing them to move farther apart and thus create more space between the molecules.

Eventually, a volume of hot water contains fewer molecules and weighs less than a volume of cold water.

As a result, hot water is less dense than cold water.

RELATED POST : WHAT IS WATER COHESION AND WHY IS IT IMPORTANT

When you place the jar containing hot water on top of the jar containing cold water, the cold water does not have to rise because it is denser than the hot water and thus remains at the bottom.

When you place the jar with cold water on top of the jar with hot water, the hot water rises to the top because it is less dense, mixing with the cold water along the way and creating purple water.

FURTHER EXTENSION ON Water Density

Try the same experiment with a jar of salted water and a jar of plain water. And let us know in the comments section which one is more dense.

Check out some of these great books on science experiments that are simple and fun to do at home if you want to stir up your children’s scientific curiosity.

(Disclosure : Some of the links below are affiliate links, meaning, at no additional cost to you, I will earn a commission if you click through and make a purchase)

Thanks for reading! We hope you enjoyed this post on hot and cold water science experiments. Be sure to check out our other posts for more fun and interesting STEM activities you can do at home with your kids. As always, if you have any questions or comments, feel free to leave them below. Happy experimenting!

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February 14, 2021 at 2:30 pm

Oh love a bit of easy STEM! maybe this is a good one for half term, if I have jars….

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How to do the hot and cold water experiment, hot and cold water experiment supply list.

2 tumbler glasses

Food coloring

Small sheet of plexiglass or other hard plastic

Don't forget your safety gear!

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Temperature and Water Density Science Experiment

Science experiment fun is the best, fun way to learn. And a fun activity to do outside in the beautiful spring weather. The perfect thing to do this time of year is to spend time outside. This temperature and water density science experiment is the perfect experiment to take outside.

This post contains affiliate links, see my disclosure policy for more information.

When you are stuck home and bored , you do science experiments that you have always wanted to try but always figured would be a huge mess. But again, boring means just doing it no matter what.

This science experiment is easy to do but does pose the risk of making a mess. Embrace it, or go outside where you won’t worry about the mess.

What you need:

• two Mason jars

What you need to do:

• Fill one jar with cold water and add food color.
• Fill the other jar with the hottest water you can while still being able to touch the jar. Add a different color of food coloring to the water.
• Place the index card over the opening of the color water jar.
• While holding the index card in place flip the jar over and on top of the jar of hot water.
• Quickly remove the index card and watch what happens.
• Redo the experiment but instead placing the jar of hot water on top.

Scroll down to find a printable version of the directions.

How to Do this Temperature and Water Density Experiment

I had a towel under the jars because I was prepared to make a huge mess. I was fully expecting the whole jar of cold green water to pour everywhere. BUT I was surprised with only a few drops of water being spilled.

Thanks to my school supply stash , I had everything for this science experiment including the index cards. I placed an index card on the top of the jar of cold water, holding it in place, I quickly flipped it over onto the top of the jar of warm water and pulled the index card out from between two.

You will see the warm water on the bottom quickly rise and mix into the cold water. The cold water jar on the bottom barely mixes with the warm water on top.

Science Experiment E-Book

What’s Happening

The molecules in hot water move faster than those in cold water . Hot water molecules bounce around and leave gaps. This makes hot water slightly less dense than cold water.

Cold water on the bottom, the denser cold water stays there.

Cold water on the top, heat molecules rise. 

Water Density

• two mason jars

Instructions

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The immiscibility of hot and cold water

The density of hot and cold water.

Does water always mix with water? You might be tempted to answer yes. But the truth is that specific parameters such as temperature and gravity can prevent two solutions of the exact nature from mixing. With this experiment, you’ll understand everything!

You will need:

• Two water glasses
• Food coloring
• A rigid plastic plate
• Otherwise: a Ziploc bag and rigid cardboard of 10 cm x 10 cm

From 6 years

Difficulty : easy

This experience requires the help of an adult

Let's experiment.

Fill a glass with tap water, add a few drops of food coloring and place it in the refrigerator overnight.

The next day, fill the second glass to the brim with hot water and add a few drops of food coloring. Place your two glasses in a dish

Place your piece of hard plastic on top of the hot water glass and gently turn it over to balance it on top of the cold water glass. The air pressure in the room should keep the plastic stuck to the glass.

With the help of an adult, carefully remove the rigid plastic at the interface and observe what happens. Do the colors mix?

This step requires a lot of agility. Also, try again if you don’t get it right the first time.

Now you will repeat the experiment and place the glass of cold water over the glass of hot water. What do you observe?

Understand the experiment

Observations.

Amusingly, you find that the colored liquids do not mix when the glass of hot water is placed on top. However, the colors mix when you use tempered water in each glass or place the cold water glass on top. Can you guess what’s happening?

Hot and cold water have different densities.

The water mixes with water, right? And yet, you notice that the colors stay on their side. Does the temperature have anything to do with it? Yes, the temperature changes the density of the water. In cold water, the water molecules are closer together. Coldwater is, therefore, denser. That means that cold water weighs more than hot water. The water molecules in hot water are further apart. So hot water is less dense than cold water. For the same volume of liquid, hot water will be lighter.

If you put the glass of hot water on top of the glass of cold water, the colors do not mix. You even get the impression that the yellow color is floating on top of the blue. When you remove the plastic, the two solutions don’t mix because the heavier cold water stays at the bottom. In contrast, the lighter hot water stays on top.

When gravity gets involved.

Suppose you invert the glasses to put the cold water solution on top, the solutions mix. That makes sense because the forces of gravity will pull down the heavier cold water. It sinks, causing the colors to mix in its path. That’s why you get green.

Why do icebergs float?

If cold water is heavier, why doesn’t ice sink? And yet, ice cubes, ice floes, and icebergs float.

In the solid-state, atoms and molecules are closer together. Solids are, therefore, denser than liquids, except in the case of ice. As water molecules form, they leave larger spaces to form crystals. This decrease in density makes them lighter.

Moreover, icebergs are formed with fresh water from glaciers. But the polar seas are salty, therefore, denser. It is for all these reasons that icebergs float instead of sinking.

Did you know?

The variations of warm and cold water in the seas and oceans form powerful ocean currents circulating on the bottom and surface of the oceans. These ocean currents help redistribute the heat stored in the oceans around the world and regulate the climate.

You can try the same experiment, but this time using salt. Saltwater is heavier than pure water. By adjusting the salinity of the water, you can reproduce the density stages in a vertical container.

Other fun experiments to do at home

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The primary colors are cyan, yellow and magenta. Three colors from which all others derive. One way to find out what the color of the felt-tip pens is made of is to play with water, a coffee filter and use the principle of capillary action. […]

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Here is a great and visual experience for you to discover the secret world of bacteria. They are very useful to us and we use them in many cooking recipes, for example. Watch how bacteria turn sugar into alcohol and carbon dioxide using a simple soda bottle and a balloon. It’s a great way to identify which drinks have sugar and which doesn’t. […]

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Water Freezing Point - Including Saltwater Tests

Posted by Admin / in Matter Experiments

It is well-known that the freezing temperature of water is 0°C or 32°F. Is there any way to change the freezing temperature of water? By performing this simple 30 minute experiment you will find out. Freezing temperature of water is tested by mixing water with some different materials and then performing freezing tests.

Materials Needed

• Clean tap water
• Cold Outside Temperature or a Freezer
• Thermometer (liquid) - Optional
• Thermometer - (atmosphere) or smart phone

EXPERIMENT STEPS

Step 1: Fill 3 small containers with water. Each container must have about the same amount of water. Do not fill the containers too full because they will need to be moved. Place a thermometer in one of the water containers and take a reading of the plain water termperature. The three liquid containers will all have the same starting temperature.

Step 2: Make a table salt (sodium Chloride) and water solution. The maximum amount of salt that typical tap water can hold until saturation is about one part salt and three parts water. We will not use this much because it takes too long to stir in the salt to get it to completely solution. Instead, we are using small containers so we only used about 2 teaspoons. Mix in all of the salt until there are no more crystals at the bottom. It will take a few minutes.

Mix a solution of table salt and water

Step 3: Next make an epsom salt (magnesium sulfate) and water solution. Epsom salt is much easier to mix with water. Again, we only used a few teaspoons full of epsom salt with our small containers.

Mix a solution of epsom salt (magnesium sulfate) and water

Step 4: Place all three containers outside or in a freezer. The outside temperature must be lower than freezing for this experiment to work. Start a stopwatch timer to begin tracking the amount of time it takes for the water samples to freeze.

Set the timer to see how long it takes for each of the water solutions to freeze

Step 5: Measure and record the starting temperature of the air outside or in the freezer.

Measure the air temperature (or freezer temperature)

Step 6: Observe the mixtures and record the time when each of the water samples freeze. This is the time when the top of the sample freezes. It will take much longer for the entire sample to freeze. We will understand the results by only observing a freezing of the surface.

Observe the solutions and record how long it takes for the water, epsom saltwater and table saltwater to freeze

Step 7: Take a measurement of the air temperature at the end of the experiment to make sure it has not changed much.

SCIENCE LEARNED

What results were observed during your experiment? You probably saw that pure water froze first, followed closely by the epsom salt solution. Saltwater takes a little longer thant the other samples to freeze, but if it is cold enough, saltwater will freeze. In general, water freezes at 0°C (32°F) and ocean saltwater freezes at 28.4°F (-1.9°C), but there are some additional factors that effect the temperature and how long each of the samples take to freeze. Here are some factors that will change either the temperature or the amount of time the samples take to freeze (or both):

• Starting Temperature of the Samples
• The air temperature
• Atmosphere - Elevation and Atmospheric Pressure
• Amount of salt or epsom salt in each solution
• Contaminants in the water
• About the author
• Back to Experiment

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Liquid Density Experiment

in Matter Experiments

Experiment with the density of different types of liquids.

Hot and Cold Water Density

Use this simple experiment to demonstrate hot and cold water density..

Water Cycle Experiment

Experiment to show all the phases of the water cycle.

Hot and Cold Water Density Ocean Currents! Experiment

Watch this portion of my video below to check out this fun science experiment!

• two empty plastic bottles
• food coloring
• hot and cold water
• laminated card
• an adult science helper

Directions: Fill up one of the bottles with cold water and dye it blue. You can also use any color you want. Fill up the other bottle with hot water and dye it yellow. You can also use any color you want. Make sure you have an adult help you with the warm water! Now, place the laminated card over the mouth of the hot water bottle. Then, flip it over and balance it on top of the other bottle as shown here! Then, carefully pull the card out of the middle. Watch as the two liquids don’t mix! It only mixes in the center. Take a look at where the two liquids meet. What do you notice?

This experiment was originally published as a YouTube Short last year. Find the original here.

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Super Cool Hot and Cold Science Experiments for Preschoolers

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Teaching the concepts of hot and cold is a fun way to get your preschooler involved in science. This is something they can feel on their own and most likely already understand the difference between by the age of 3, so the experiment isn’t beyond the grasp of their understanding. And who doesn’t love to play with water and ice! Let’s do hot and cold science experiments for preschoolers!

(As an   Amazon Associate I earn from qualifying purchases. If you click on the links, you will not pay any extra, but I will earn a small commission that will help us finance our creative life. Thanks!)

What You Need for Hot and Cold Science Experiments for preschoolers:

• Hot water (not too hot)
• Optional: a small stone or rock

How to Do the Science Experiment for preschoolers:

Before this experiment, we read the story Fireflies in the Night as part of our Summertime Activity Plans. The story talks about how hot and cold affect the firefly’s light, so it provides the perfect opportunity to then talk about hot and cold.

First, add water to the bowls.

To one bowl add the warm water. To the other add cool water from the faucet.

Then give your little one a cup of ice. Let them touch the ice and talk about what it feels like. Then have them dip their fingers in the bowl of warm water to feel the difference between the two.

Next, let your preschooler pour a few ice cubes in the cool water. While they sit in the water, also put a few in the hot water. Ask them what happens to the ice cubes as they watch.

Why did the ice cubes melt? What does the water feel like now?

Now look back at the cool water bowl. What has happened to the ice? It shouldn’t have melted as much, but the water should be cooler to the touch as well.

Allow them to play with the water and ice cubes as much as they want, keeping the discussion going about what they feel and why they think it happened. Just have fun with it!

Extra credit science experiment:

If you want to keep the experiment going, give your toddler the warm rock now.

(To warm the rock, put it in a 200 F oven for just a few minutes. You want it warm to the touch, but not hot enough to burn.)

Now put an ice cube on top of the warm rock. What happens to the ice cube? How does the rock feel now? Put the rock in a bowl of ice. What happens to the rock?

Again, let your little one lead the experiment and have fun as they explore the concepts of hot and cold!

If you loved this one of our science experiments for preschoolers, check out our others!

Fun and Easy Sun and Moon Art Project for Preschoolers

How to Learn the Phases of the Moon

Rocket Man Craft for Preschoolers

Awesome Floating and Sinking Grapes Science Experiment for Preschoolers

Super Summertime Activity Plans for Preschoolers

Lemon Volcanoes: an Amazing Science Experiment for Preschoolers

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Check out this cool science experiment video that focuses on the process of diffusion. Diffusion involves molecules moving from areas of higher concentration to areas of lower concentration. In this experiment the diffusion of food coloring in hot and cold water shows how temperature effects the rate of diffusion, with the process being much faster in hot water than in cold water. Science Kids ©  |     |     |     |     |     |     |     |     |     |     |     |     |     |  Updated: Oct 9, 2023 Summer holiday science: turn your home into a lab with these three easy experiments Associate Professor in Biology, University of Limerick Disclosure statement Audrey O'Grady receives funding from Science Foundation Ireland. She is affiliated with Department of Biological Sciences, University of Limerick. University of Limerick provides funding as a member of The Conversation UK. View all partners Many people think science is difficult and needs special equipment, but that’s not true. Science can be explored at home using everyday materials. Everyone, especially children, naturally ask questions about the world around them, and science offers a structured way to find answers. Misconceptions about the difficulty of science often stem from a lack of exposure to its fun and engaging side. Science can be as simple as observing nature, mixing ingredients or exploring the properties of objects. It’s not just for experts in white coats, but for everyone. Don’t take my word for it. Below are three experiments that can be done at home with children who are primary school age and older. Extract DNA from bananas DNA is all the genetic information inside cells. Every living thing has DNA, including bananas. Did you know you can extract DNA from banana cells? What you need: ¼ ripe banana, Ziploc bag, salt, water, washing-up liquid, rubbing alcohol (from a pharmacy), coffee filter paper, stirrer. What you do: Place a pinch of salt into about 20ml of water in a cup. Add the salty water to the Ziploc bag with a quarter of a banana and mash the banana up with the salty water inside the bag, using your hands. Mashing the banana separates out the banana cells. The salty water helps clump the DNA together. Once the banana is mashed up well, pour the banana and salty water into a coffee filter (you can lay the filter in the cup you used to make the salty water). Filtering removes the big clumps of banana cells. Once a few ml have filtered out, add a drop of washing-up liquid and swirl gently. Washing-up liquid breaks down the fats in the cell membranes which makes the DNA separate from the other parts of the cell. Slowly add some rubbing alcohol (about 10ml) to the filtered solution. DNA is insoluble in alcohol, therefore the DNA will clump together away from the alcohol and float, making it easy to see. DNA will start to precipitate out looking slightly cloudy and stringy. What you’re seeing is thousands of DNA strands – the strands are too small to be seen even with a normal microscope. Scientists use powerful equipment to see individual strands. Learn how plants ‘drink’ water What you need: celery stalks (with their leaves), glass or clear cup, water, food dye, camera. Fill the glass ¾ full with water and add 10 drops of food dye. Place a celery stalk into the glass of coloured water. Take a photograph of the celery. For two to three days, photograph the celery at the same time every day. Make sure you take a photograph at the very start of the experiment. What happens and why? All plants, such as celery, have vertical tubes that act like a transport system. These narrow tubes draw up water using a phenomenon known as capillarity. Imagine you have a thin straw and you dip it into a glass of water. Have you ever noticed how the water climbs up the straw a little bit, even though you didn’t suck on it? This is because of capillarity. In plants, capillarity helps move water from the roots to the leaves. Plants have tiny tubes inside them, like thin straws, called capillaries. The water sticks to the sides of these tubes and climbs up. In your experiment, you will see the food dye in the water make its way to the leaves. Build a balloon-powered racecar What you need: tape, scissors, two skewers, cardboard, four bottle caps, one straw, one balloon. Cut the cardboard to about 10cm long and 5cm wide. This will form the base of your car. Make holes in the centre of four bottle caps. These are your wheels. To make the axles insert the wooden skewers through the holes in the cap. You will need to cut the skewers to fit the width of the cardboard base, but leave room for the wheels. Secure the wheels to the skewers with tape. Attach the axles to the underside of the car base with tape, ensuring the wheels can spin freely. Insert a straw into the opening of a balloon and secure it with tape, ensuring there are no air leaks. Attach the other end of the straw to the top of the car base, positioning it so the balloon can inflate and deflate towards the back of the car. Secure the straw with tape. Inflate the balloon through the straw, pinch the straw to hold the air, place the car on a flat surface, then release the straw. The inflated balloon stores potential energy when blown up. When the air is released, Newton’s third law of motion kicks into gear: for every action, there is an equal and opposite reaction. As the air rushes out of the balloon (action), it pushes the car in the opposite direction (reaction). The escaping air propels the car forward, making it move across the surface. Science experiments Associate Professor, Psychology Service Delivery Fleet Coordinator Manager, Centre Policy and Translation Newsletter and Deputy Social Media Producer College Director and Principal | Curtin College Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. View all journals Explore content About the journal Publish with us Sign up for alerts 14 August 2024 What is the hottest temperature humans can survive? These labs are redefining the limit Carissa Wong You can also search for this author in PubMed   Google Scholar Dousing the skin and clothes with water is one cost-effective way to protect the body from overheating. Credit: Rehman Asad/NurPhoto/Getty This story is part of special report on science and extreme heat. Read about the effects that extreme heat has on the body , how climate change is intensifying health problems and the record-breaking warming at the Great Barrier Reef . In 2019, physiologist Ollie Jay started designing a chamber that could simulate the heatwaves of today and of the future. Eighteen months later, the Aus$2-million (US$1.3-million) structure was built, packed up in Brisbane, Australia, and driven 1,000 kilometres to the University of Sydney, where it was lifted to the top floor of a shiny glass building. Now, researchers including Jay are using it to test the limits of human survival in extreme heat , which are surprisingly poorly understood. Cities must protect people from extreme heat “The trouble is that, today, you have these conditions that can sound hot, but we don’t really know what it’s going to do to people,” says Jay, who directs the heat and health laboratory at the University of Sydney. “By simulating those conditions and exposing people to them, under careful medical supervision, we can better understand the physiology of how people will respond,” he says. Jay’s team is also exploring which cooling strategies work best to reduce the health risks of heat exposure. As climate change heats Earth, blistering days have become a regular feature of weather reports worldwide. Last month, the record for the world’s hottest day was broken twice, and the United Nations made a global call for action on extreme heat, to help vulnerable people, workers and economies to cope using science. Around 70% of the global workforce — 2.4 billion people — are now at high risk of extreme heat, it said. Despite this, public advice on how to cope with high temperatures is poor, and ways that people can effectively cool themselves have not been well studied. “If you look at heat advisories from well-respected organizations like the US Centres for Disease Control and Prevention, the World Health Organization, they’re fraught with errors when it comes to human physiology,” says Larry Kenney, a physiologist at Pennsylvania State University in University Park. Researchers at the University of Sydney monitor how heat is affecting a pregnant woman in their climate chamber. Credit: University of Sydney/Stefanie Zingsheim Chamber of heat Jay’s team is using its state-of-the-art climate chamber to investigate the conditions under which heat threatens life, how, and what practical, evidence-based ways there are to stay cool. The chamber is a room 4 metres by 5 metres. Researchers can dial the temperature up or down by 1 °C every minute — from 5 °C to a searing 55 °C — control windspeed and simulate sunlight using infrared lamps. They can also fine-tune humidity, a key variable that influences heat’s effects on the body. “It’s quite the engineering feat,” says Jay. Extreme heat harms health — what is the human body’s limit? Trial participants can eat, sleep and exercise inside the chamber; researchers pass food and other items to them through a hatch. Sensors attached to them send information to the adjacent control room, which processes data on variables including heart rate, breathing, sweating and body temperature. Heat thresholds for humans have been poorly defined in part because public-health bodies have over-relied on a theoretical study published 1 in 2010, says Jay. In that paper, researchers used mathematical models to define the ‘wet-bulb temperature’ (WBT) at which a young, healthy person would die after six hours. WBT is a measure that scientists use when studying heat stress because it accounts for the effects of heat and humidity. The models churned out a WBT of 35 °C as the limit of human survival. At that threshold, the body’s core temperature would rise uncontrollably. But the model treated the human body as an unclothed object that doesn’t sweat or move, making the result less applicable to the real world. Ollie Jay’s lab is studying how heat affects people who are exercising to mimic everyday activities. Credit: University of Sydney/Stefanie Zingsheim Despite this, countless public-health bodies adopted it — even the Intergovernmental Panel on Climate Change — reducing the motivation to obtain a more relevant number, says Jay. “It’s a basic physical model with many limitations — but nearly everyone’s using this.” Lowered limit In a 2021 study, Kenney and his colleagues provided a better estimate: a WBT survival limit of around 31 °C. They calculated it by tracking the core body temperature of young, healthy people under different combinations of temperature and humidity while they were cycling. “You do still see the 35 °C wet-bulb temperature tossed around, but people are starting to come around to the limit defined by Kenney’s lab,” says Robert Meade, a heat and health researcher at Harvard University in Cambridge, Massachusetts. Kenney’s group also works with a climate chamber, and there are dozens worldwide, many dedicated to sports science. But Kenney says that just a few groups, including Jay’s, are at the forefront of using them to better understand how people cope in extreme heat. Physiological model Jay’s team is now testing a mathematical model of how the body copes in extreme heat, which it published 3 last year. The model uses data from studies that have measured sweating capacity in older and younger people, and it follows physical laws to predict how heat is transferred between the body and environment. “The fact that they incorporated physiology, which very few models do, and do well — I think this makes it the best model right now out there,” says Kenney, who has collaborated with Jay on other research. Most models of the body’s response to heat focus on young, healthy people in the shade. But Jay and his team’s model estimated the limits of survival in the shade and sunlight across ages and while people were resting or exercising. Among their results, they estimated WBT survival limits of between 26 °C and 34 °C for young people and 21 °C to 34 °C for older people. “The flexibility and the ability to very easily assess these different scenarios is the key advance of the model,” says Meade. Workers in a garment factory in Bangladesh, where long hours and hot weather can affect employees’ health. Credit: Kazi Salahuddin Razu/NurPhoto/Getty Unsurprisingly, the model suggests that survival limits are lower when people are exposed to the Sun versus in the shade, and for people over 65 years old compared with those aged 18–40. The team also used the model to define livability limits — conditions in which older and younger people could safely carry out tasks such as desk-work, walking, climbing stairs, dancing and heavy lifting. Despite its strengths, the model still needs to be tested further in people, says Meade. To do this, Jay’s team is first exposing young, healthy people in the climate chamber to combinations of temperature and humidity while monitoring variables such as their core body temperature, heart rate and sweating up to a temperature threshold above which it would be unsafe. Read the paper: Extreme escalation of heat failure rates in ectotherms with global warming In future trials, the researchers plan to test the body’s response to heat in shady and sunlit conditions, across ages and during exercise. They will use data from these trials to improve the model, which, in turn, can be used to develop better health advice for people most at risk in high heat. Need to chill The lab’s other focus — finding effective cooling strategies — involves mimicking the conditions of environments where heat can affect workers’ health. In one trial, Jay’s team is testing cooling strategies that could help garment-factory workers in Bangladesh, where people typically work long hours in hot climates, with little access to air conditioning. The researchers previously measured the heat and humidity across three floors of a clothing factory in the capital, Dhaka. “We recreated those conditions in the chamber, and the work that people did — the women did sewing and the men did ironing,” he says. The trial participants wore clothing that workers would typically wear in the factory. Participants in Jay’s lab have recreated the conditions of a garment factory in their climate chamber to investigate effective cooling methods. Credit: University of Sydney/Stefanie Zingsheim Across some 240 climate-chamber trials, the team measured people’s body functions and their work productivity, says Jay, “because one of the problems is that people slow down when they get hot”. The scientists tested cooling methods such as using fans and regularly drinking water, and simulated the effects of changing the colour of the factory roof. The researchers plan to submit their results to a journal. Jay’s team has also explored how electric fans and skin-wetting affect heart strain in older people, across different combinations of heat and humidity. The researchers found that, in humid conditions, fan use reduced heart strain up to an air temperature of at least 38 ˚C. But in dry heat, fan use increased heart strain. Wetting the skin was beneficial in both dry and humid heat. “Identifying the situations in which common cooling strategies, such as fan use and dousing the skin with water, work best is essential to protect public health,” says Meade. Low-tech cooling Jay and his colleagues have already popularized a method for cooling babies in prams. “On a hot day, people are covering their baby strollers with these white muslin cloths — but there’s all this contention as to whether it’s a good or bad thing,” he says. In a 2023 study 4 , the team found that a dry, white muslin cloth can heat up prams by more than 2.5 °C, but a damp one had the best cooling effect. “It extracts the latent heat energy from inside the pram and keeps it cooler by about 5 °C,” he says. A man is treated for heatstroke in Varanasi, India, which has been experiencing periods of severe heat since May. The study drew media attention. “What was pretty cool is, two weeks later, I’m walking around where I live and I start seeing parents pushing along their white muslin cloths with a spray bottle,” he says. The team has also helped to shape a global heat-alert system released by the Google Chrome browser for its users worldwide. “If it knows where you are, and the heat exceeds a certain threshold, then you get an extreme-heat warning,” he says. The alert provides cooling tips such as to drink one cup of water per hour and to wet skin and clothing. Next year, Jay’s lab will track how heat affects birth outcomes and maternal health in pregnant women in Bangladesh. He’s seeking funding to conduct a randomized controlled trial of cooling strategies in India during the hot season. Jay’s ultimate goal is to protect people’s health in a world that’s becoming ever more hostile. “When I first came over to Sydney, I basically took a big demotion — there was an old chamber that wasn’t really working well, and I had about Aus$16,500 of start-up funding,” says Jay. “We have been lucky and fortunate to be able to bring in some good funding, and make some good traction in this area.” doi: https://doi.org/10.1038/d41586-024-02422-5 Sherwood, S. C. & Huber, M. Proc. Natl Acad. Sci. USA 107 , 9552–9555 (2010). Article   PubMed   Google Scholar   Vecellio. D. J., Wolf, S. T., Cottle, R. M. & Kenney, W. L. J. Appl. Physiol. 132 , 340–345 (2022). Vanos, J. et al. Nature Commun. 14 , 7653 (2023). Bin Maideen, M. F. et al. Ergonomics 66 , 1935–1949 (2023). 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Quick links Explore articles by subject Guide to authors Editorial policies To revisit this article, visit My Profile, then View saved stories . The Big Story Newsletters Steven Levy's Plaintext Column WIRED Classics from the Archive WIRED Insider WIRED Consulting The Physics of Cold Water May Have Jump-Started Complex Life The original version of this story appeared in Quanta Magazine . Once upon a time, long ago, the world was encased in ice. That’s the tale told by sedimentary rock in the tropics, many geologists believe. Hundreds of millions of years ago, glaciers and sea ice covered the globe. The most extreme scenarios suggest a layer of ice several meters thick even at the equator. This event has been called Snowball Earth, and you’d think it would be a terrible time to be alive—and maybe, for some organisms, it was. However, in a warmer period between glaciations, the first evidence of multicellular animals appears, according to some interpretations of the geological record. Life had taken a leap. How could the seeming desolation of a Snowball Earth line up with this burst of biological innovation? A series of papers from the lab of Carl Simpson proposes an answer linked to a fundamental physical fact: As seawater gets colder, it gets more viscous, and therefore more difficult for very small organisms to navigate. Imagine swimming through honey rather than water. If microscopic organisms struggled to get enough food to survive under these conditions, as Simpson’s modeling work has implied, they would be placed under pressure to change—perhaps by developing ways to hang on to each other, form larger groups, and move through the water with greater force. Maybe some of these changes contributed to the beginning of multicellular animal life. To test the idea, Simpson, a paleobiologist at the University of Colorado, Boulder, and his team conducted an experiment designed to see what a modern single-celled organism does when confronted with higher viscosity. Over the course of a month, he and his graduate student Andrea Halling watched how a type of green algae—members of a lab-friendly species that swims with a tail-like flagellum—formed larger, more coordinated groups as they encountered thicker gel. The algae collectively motored through the fluid to keep up their feeding pace. And, intriguingly, the groups of cells remained stuck together for 100 generations after the experiment ended. The research offers a novel take on the emergence of multicellular life, said Phoebe Cohen , a paleontologist at Williams College who has spoken with Simpson about his idea over the years but was otherwise uninvolved with the work. The field is overflowing with papers about triggers for the evolution of animal multicellularity that draw on geochemical measurements, she said, but few consider the biology of individual organisms. To re-create Snowball Earth conditions in the lab, biologists placed swimming algal cells into gel of varying viscosity. The cells that made it to the thickest, outer layer displayed signs of collective behavior—a potential step toward multicellularity. “I’m very charmed by the idea, by the experimental setup as well,” Cohen said. “It’s really wonderful to see work saying: What’s actually going on here? How are these early organisms actually experiencing their environment?” The experiment comes with a few caveats, and the paper has yet to be peer-reviewed; Simpson posted a preprint on biorxiv.org earlier this year. But it suggests that if Snowball Earth did act as a trigger for the evolution of complex life, it might be due to the physics of cold water. A Frozen Paradox “Snowball Earth” was on everyone’s lips when Simpson was an undergraduate in the late 1990s. In 1992, the geochemist Joseph Kirschvink had pointed out that there was good geological evidence for a global glaciation event in the ancient past; crucially, he provided a model for how all that ice might have been coerced to melt again. Then, in 1998, the Harvard geologist Paul Hoffman and colleagues published a landmark paper that applied these ideas to observations of sedimentary deposits in Namibia. They agreed: The rocks indicated the presence of glaciers in the warmest parts of the world around 700 million years ago. Even back then, the timing of Snowball Earth troubled Simpson. “That was a total paradox for me,” he said. “There’s no way Snowball Earth was real, given how much interesting evolution was happening at the time.” Before Snowball Earth, fossils are tiny, he said. Afterward, they are big and complicated. It is difficult to precisely date when animals arose, but an estimate from molecular clocks—which use mutation rates to estimate the passage of time—suggests that the last common ancestor of multicellular animals emerged during the era known as the Sturtian Snowball Earth, sometime between 717 million and 660 million years ago. Large, unmistakably multicellular animals appear in the fossil record tens of millions of years after the Earth melted following another, shorter Snowball Earth period around 635 million years ago. The paradox—a planet seemingly hostile to life giving evolution a major push—continued to perplex Simpson throughout his schooling and into his professional life. In 2018, as an assistant professor, he had an insight: As seawater gets colder, it grows thicker. It’s basic physics—the density and viscosity of water molecules rises as the temperature drops. Under the conditions of Snowball Earth, the ocean would have been twice or even four times as viscous as it was before the planet froze over. Simpson wondered what it would have been like to be a microscopic organism in the ocean during Snowball Earth. Maybe the whole thing wasn’t so paradoxical after all. To very small single-celled creatures, thick seawater would have posed some big problems. Bacteria feed by diffusion—the movement of nutrients through water from areas of high concentration to low concentration—and tend to wait for food to come to them. However, at low temperatures, diffusion slows down. Nutrients don’t travel as quickly or as far. For cells, living in a cold and more viscous fluid means getting less to eat. Even very small organisms that can propel themselves, such as cells with flagella, move more slowly in cold water. As a result, they encounter food less frequently. A bigger organism, on the other hand, can navigate thicker waters without much trouble. A cluster of cells has the benefit of inertia: Their combined mass is large enough to allow them to build up steam and barrel through thicker fluid. “At some point, you are too big for this to matter,” Simpson said. In 2021, he published his hypothesis that Snowball Earth viscosities would have put a significant strain on organisms’ ability to feed themselves and could have spurred some to evolve multicellularity. Then, with collaborators at the Santa Fe Institute, he designed mathematical models of small creatures—single cells that fed by diffusion and self-propelling cells that fed by moving around—living in thicker and thicker fluids. In the models, posted to biorxiv.org at the end of 2023 and recently published in the peer-reviewed Proceedings of the Royal Society B , the diffusion feeders responded to thicker fluids by shrinking in size. The self-propelling cells, equipped by the equations with the ability to cling together if needed, formed larger and larger multicellular groups. This suggested that if there were already multicellular organisms when Snowball Earth occurred—or at least organisms with the ability to take on multicellular forms—the thicker fluid could have given them a reason to get bigger. Paleobiologist Carl Simpson has led a body of work—computer modeling and experiments with living organisms—to study whether the physics of cold water causes cells to act collectively like a multicellular creature. The results were intriguing, but they were only computer models. Simpson thought: Well, what if they did this with real organisms? The geologist Boswell Wing, a colleague at the University of Colorado, Boulder, had a colony of Chlamydomonas reinhardtii in his lab. These algae have twirling flagella that allow them to move under their own power. They are usually unicellular. But they can switch into a multicellular form under certain stressful conditions. Would higher viscosity, like that of the oceans during Snowball Earth, prove to be one of them? Life in Thick Water There’s no way for biologists to travel back in time to test the real conditions of Snowball Earth, but they can try to re-create aspects of them in the lab. In an enormous, custom-made petri dish, Halling and Simpson created a bull’s-eye target of agar gel—their own experimental gauntlet of viscosity. At the center, it was the standard viscosity used for growing these algae in the lab. Moving outward, each concentric ring had higher and higher viscosity, finally reaching a medium with four times the standard level. The scientists placed the algae in the middle, turned on a camera, and left them alone for 30 days—enough time for about 70 generations of algae to live, swim around for nutrients and die. Andrea Halling led experiments with living creatures to see how life might have responded to evolutionary pressures 600 million years ago. Halling and Simpson suspected that as the algae reproduced and crowded the center circle of normal viscosity, any algal cells that could handle the thicker medium would spread outward. Perhaps those that reached the outermost ring would look and behave differently from those that remained in the center. Simpson was particularly curious as to whether algae that made it into the highest viscosity ring would find ways to increase their swimming speed. The algae are photosynthetic, so they get energy from the sun. But they need to pick up nutrients such as phosphorus from the environment, so movement is still important to their survival. Maintaining the same level of nutrients in high-viscosity surroundings would require them to find a way to keep up their speed. After 30 days, the algae in the middle were still unicellular. As the scientists put algae from thicker and thicker rings under the microscope, however, they found larger clumps of cells. The very largest were wads of hundreds. But what interested Simpson the most were mobile clusters of four to 16 cells, arranged so that their flagella were all on the outside. These clusters moved around by coordinating the movement of their flagella, the ones at the back of the cluster holding still, the ones at the front wriggling. Comparing the speed of these clusters to the single cells in the middle revealed something interesting. “They all swim at the same speed,” Simpson said. By working together as a collective, the algae could preserve their mobility. “I was really pleased,” he said. “With the coarse mathematical framework, there were a few predictions I could make. To actually see it empirically means there’s something to this idea.” Intriguingly, when the scientists took these little clusters from the high-viscosity gel and put them back at low viscosity, the cells stuck together. They remained this way, in fact, for as long as the scientists continued to watch them, about 100 more generations. Clearly, whatever changes they underwent to survive at high viscosity were hard to reverse, Simpson said—perhaps a move toward evolution rather than a short-term shift. ILLUSTRATION Caption: In gel as viscous as ancient oceans, algal cells began working together. They clumped up and coordinated the movements of their tail-like flagella to swim more quickly. When placed back in normal viscosity, they remained together. Credit: Andrea Halling Modern-day algae are not early animals. But the fact that these physical pressures forced a unicellular creature into an alternate way of life that was hard to reverse feels quite powerful, Simpson said. He suspects that if scientists explore the idea that when organisms are very small, viscosity dominates their existence, we could learn something about conditions that might have led to the explosion of large forms of life. A Cell’s Perspective As large creatures, we don’t think much about the thickness of the fluids around us. It’s not a part of our daily lived experience, and we are so big that viscosity doesn’t impinge on us very much. The ability to move easily—relatively speaking—is something we take for granted. From the time Simpson first realized that such limits on movement could be a monumental obstacle to microscopic life, he hasn’t been able to stop thinking about it. Viscosity may have mattered quite a lot in the origins of complex life, whenever that was. “[This perspective] allows us to think about the deep-time history of this transition,” Simpson said, “and what was going on in Earth’s history when all the obligately complicated multicellular groups evolved, which is relatively close to each other, we think.” Other researchers find Simpson’s ideas quite novel. Before Simpson, no one seems to have thought very much about organisms’ physical experience of being in the ocean during Snowball Earth, said Nick Butterfield of the University of Cambridge, who studies the evolution of early life. He cheerfully noted, however, that “Carl’s idea is fringe.” That’s because the vast majority of theories about Snowball Earth’s influence on the evolution of multicellular animals, plants, and algae focus on how levels of oxygen, inferred from isotope levels in rocks, could have tipped the scales in one way or another, he said. That novelty is a strength, said the geobiologist Jochen Brocks of the Australian National University. However, in his assessment, Simpson’s hypothesis makes a few logical leaps that don’t hold up. It’s not clear that the earliest animals would have been swimming freely in water, Brocks said. Some of the first fossils that can be confidently called “animals” were anchored on the ocean floor. Perhaps more importantly, the timeline of animal origins is very uncertain. Some estimates suggest that the Snowball Earth period might line up with the last common ancestor of animals. But these are based on molecular inferences from DNA that are hard to confirm, Brocks said. In his opinion, it’s difficult to say how much importance to assign to this era. Butterfield also remarked on this uncertainty: “There’s no evidence of anything getting large until quite a bit after [Snowball Earth].” That said, Brocks found Simpson’s experiment quite clever and beautiful. The fact that organisms might respond to high viscosity by developing collective behavior deserves to be better understood, he said—whether Snowball Earth led to the evolution of complex animal life or not. “Putting this into our repertoire of thinking about why these things evolved—that is the value of the entire thing,” he said. “It doesn’t matter if it was Snowball Earth. It doesn’t matter if it happened before or after. Just the idea that it can happen, and happen quickly.” Brocks is curious about what would happen if a similar experiment were performed with choanoflagellates, little creatures that are more closely related to animals than algae are. They rely entirely on hunting to get food—they can’t photosynthesize—so they would be especially vulnerable to slowdowns caused by high viscosity. If they started to take on multicellular forms under those conditions, that would suggest that Simpson’s results represent a more general truth about how life responds to its environment. “It would be absolutely ultra-exciting,” he said. Simpson is, in fact, currently working with choanoflagellates. Right now, he is trying to understand how they live . “They’re really beautiful and complicated creatures,” he said. They can take on many different forms: There are fast swimmers with long flagella, slow swimmers that meander, ones that stick to a surface to grow. “They can grow these little tendrils off the tip and walk around like on stilts; they have sex, and they fuse, and they form chain colonies and rosette colonies … and if you squeeze them, apparently they’ll lose their flagella and turn into an amoeba,” he said. When it comes to responding to the challenges of a radical new environment, he reflected, “they’ve got a lot to work with.” Original story reprinted with permission from Quanta Magazine , an editorially independent publication of the Simons Foundation whose mission is to enhance public understanding of science by covering research developments and trends in mathematics and the physical and life sciences. You Might Also Like … In your inbox: Our biggest stories , handpicked for you each day How one bad CrowdStrike update crashed the world’s computers The Big Story: How soon might the Atlantic Ocean break ? Welcome to the internet's hyper-consumption era 116 IMAGES Hot vs Cold Water Experiment (Chemistry) Hot And Cold Water Science Experiment Hot And Cold Water Experiment Balloon In Hot and Cold Water How Atoms react in Hot and Cold Water. Science Experiment for Kids How to Do the Hot and Cold Water Density Experiment COMMENTS Hot & Cold Water Science Experiment 1 Jar of hot water. 1 Plastic card. 1 Spoon. 1 Large dish or a baking pan. Red and blue food coloring. Steps to follow. Add a few drops of red food color into the hot water jar and stir it cautiously with a spoon. Similarly, add a few drops of blue food color into the cold water jar and stir it with a spoon. Easy Water Temperature Science Experiment + Video & Lab Kit Water Temperature Science Experiment Instructions. Step 1 - Begin by preparing three identical jars of water. Fill one jar with cold water, one jar with room temperature water, and one jar with hot water. Helpful Tip: For cold water, fill the jar and put it in the fridge for an hour or two. For the room temperature water, fill the jar and ... Hot and Cold Water Density Experiment The demonstration works as cold water is more dense than hot water so the hot water sits on top of the cold. When water is heated, water molecules move around faster, bounce off each other and move further apart. As there's more space between the water molecules the density of warmer water is less than the same volume of cooler water. How to Do the Hot and Cold Water Density Experiment First, do the experiment with the cold water on the bottom. Place the index card over the mouth of the hot water jar. Press slightly to make a seal. Flip the jar over and place it on top of the cold water jar (make sure it's a color combo that will make a secondary color). Line up the lip of the jars and carefully pull the card out. Hot and Cold Water Density Experiment The cold water is more dense than the hot water. The red and blue coloring will stay separated until the water temperatures start to even out. This will actually take quite a while if the very hot and reasonably cold water is used for the experiment. The experiment cannot really be performed with the hot water starting on the bottom. The hot ... Balloon In Hot and Cold Water Make sure the bottle is empty before you attach the Balloon to it. Repeat the same method and prepare another set of water bottle and Balloon using the other empty bottle. Step-4: In this step, keep the ballon attached bottle inside the container, which consists of hot water. Learn about Hot and Cold Temperature: Easy Science Experiments for Kids Fill a pitcher with water and add drops of blue food coloring. Fill an ice tray with the blue water and put it in the freezer until the ice is solid. Fill a container with room temperature water and place the blue ice inside. The ice should float and the blue water that melts from the ice cube should sink. Hot vs Cold Water Experiment (Chemistry) In this experiment, you can visualize the difference in density between hot and cold water. Using the food coloring and a thermal infrared camera you can re... Hot Water Density Experiment This simple density science experiment starts with placing two glasses with yellow water on top of two glasses with blue water. When we remove cards that se... Hot And Cold Water Science Experiment 2 Amazing Hot and Cold Water Density ExperimentsThe science will amaze you if you just look close enough to things that surround you. What do you think would... Hot & Cold Water Science Experiment This experiment by HooplaKidzLab demonstrates how the more dense cold water sinks — those molecules are closer together — pushing the slightly less dense hot water to float on top. Air behaves in the same way… think of hot air balloons as an example, or a multi-story house on a hot day, where the top floors are warmer than the bottom ... How to Demonstrate Diffusion with Hot and Cold Water In one glass, pour the cold water and in the other hot water. As we mentioned, near-boiling water for hot and regular temperature water from the pipe will be good to demonstrate the diffusion. Drop a few drops of food coloring in each cup. 3-4 drops are enough and you should not put too much food color. Hot and Cold Water Science EXPERIMENT Fill one jar with cold water and the other with hot water. Pour blue food coloring into the cold water and red food coloring into the hot water. Make sure both jars are completely filled with water. To avoid spills, place them in the shallow plate. Tap the card gently on top of the hot water jar. The card should completely cover the jar's mouth. How to Do Hot and Cold Water Science Experiment Hot and Cold Water Experiment Supply List. Hot water. Cold water. 2 tumbler glasses. Food coloring. Small sheet of plexiglass or other hard plastic. Don't forget your safety gear! Lab coat . Safety goggles. Temperature and Water Density Science Experiment Place the index card over the opening of the color water jar. While holding the index card in place flip the jar over and on top of the jar of hot water. Quickly remove the index card and watch what happens. Redo the experiment but instead placing the jar of hot water on top. Scroll down to find a printable version of the directions. Density hot water and cold water In cold water, the water molecules are closer together. Coldwater is, therefore, denser. That means that cold water weighs more than hot water. The water molecules in hot water are further apart. So hot water is less dense than cold water. For the same volume of liquid, hot water will be lighter. Water Freezing Temperature Experiment EXPERIMENT STEPS. Step 1: Fill 3 small containers with water. Each container must have about the same amount of water. Do not fill the containers too full because they will need to be moved. Place a thermometer in one of the water containers and take a reading of the plain water termperature. The three liquid containers will all have the same ... Hot & Cold Water Science Experiment Hot And Cold Water Science Experiment. Instructions for a fun experiment to teach kids the difference between the density of hot water and the density of col... Hot and Cold Water Density Ocean Currents! Experiment Experiment. Watch this portion of my video below to check out this fun science experiment! Directions: Fill up one of the bottles with cold water and dye it blue. You can also use any color you want. Fill up the other bottle with hot water and dye it yellow. You can also use any color you want. Make sure you have an adult help you with the warm ... Super Cool Hot and Cold Science Experiments for Preschoolers Hot water (not too hot) Optional: a small stone or rock; How to Do the Science Experiment for preschoolers: Before this experiment, we read the story Fireflies in the Night as part of our Summertime Activity Plans. The story talks about how hot and cold affect the firefly's light, so it provides the perfect opportunity to then talk about hot ... Dissolving Sugar at Different Heats Sugar cubes. Cold water in a clear glass. Hot water in a clear glass (be careful with the hot water) Spoon for stirring. Instructions: Make sure the glasses have an equal amount of water. Put a sugar cube into the cold water and stir with the spoon until the sugar disappears. Repeat this process (remembering to count the amount of sugar cubes ... Diffusion of Food Coloring in Hot & Cold Water Diffusion of Food Coloring. Check out this cool science experiment video that focuses on the process of diffusion. Diffusion involves molecules moving from areas of higher concentration to areas of lower concentration. In this experiment the diffusion of food coloring in hot and cold water shows how temperature effects the rate of diffusion ... Summer holiday science: turn your home into a lab with these three easy In your experiment, you will see the food dye in the water make its way to the leaves. Build a balloon-powered racecar What you need: tape, scissors, two skewers, cardboard, four bottle caps, one ... What is the hottest temperature humans can survive? These labs are "The trouble is that, today, you have these conditions that can sound hot, but we don't really know what it's going to do to people," says Jay, who directs the heat and health laboratory ... Hot and Cold Water Experiment What is the transfer of energy? Visualize the transfer of energy and movement of molecules in this easy science experiment for kids! Enjoy this simple experi... NASA's Quantum Cold Atom Lab Just Made Space Even Cooler—Literally NASA's Cold Atom Lab on board the ISS. NASA/JPL-Caltech NASA is experimenting with the use of quantum technology to measure gravity, magnetic fields, and other forces in space. The space agency ... The Physics of Cold Water May Have Jump-Started Complex Life Paleobiologist Carl Simpson has led a body of work—computer modeling and experiments with living organisms—to study whether the physics of cold water causes cells to act collectively like a ... essay homework paper phd project resume review study thesis