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
• Cold Water
• Room Temperature Water
• Hot Water
• Food Coloring

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

Water Temperature Science Experiment Step by Step Instructions

How Does The Experiment Work?

Although the jars of water look the same, the water temperature is different. Temperature affects how quickly the molecules that make up water move.

In hot water, water molecules move faster because they have more thermal energy. In cold water, water molecules move more slowly because they have less thermal energy.

When food coloring is added to the water, it begins to spread throughout the water. This spreading happens through a process called diffusion. The food coloring spreads faster in hot water because the water molecules are moving faster. In cold water, the molecules move more slowly, so the food coloring takes longer to spread.

The room temperature water falls between the hot and cold water. The food coloring will generally spread faster than it does in cold water, but more slowly than it does in hot water.

This experiment shows how temperature can affect the speed at which a substance spreads through water. By comparing the jars, we can observe how hot, room temperature, and cold water affect the movement of food coloring.

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

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Materials

• Three Glass Jars
• Cold Water
• Room Temperature Water
• Hot Water
• Food Coloring

Instructions

1. 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.
2. Place 2-3 drops of food coloring in each jar.
3. Observe what happens to the food coloring. Does it behave differently in each jar?