Exploring Thermodynamics With Kids: Activities To Teach About Freezing, Melting, And Molecular Movement

Studying thermodynamics starts at a very young age, even if we don’t use that big word.  Thermodynamics is the branch of science that is concerned with the relationship between heat, work, temperature, and energy.  It studies the amount of energy moving in and out of a system.

Young children look at thermodynamics as studying what is hot and cold.  They learn that ice and the air can feel cold. They understand the need to wear a coat, and when they get hot, they take it off. They discover that everything they touch has a temperature.

It is important to expand on this concept so they do not grow up with misconceptions.  The basic definition of energy is the ability to do work.  To do work means an object has to move.  That can be at an atomic level or at a larger level.  

There are many types of energy.  Below, you will find ideas for exploring thermal energy.  Thermal energy refers to the internal energy of a system that is responsible for its temperature.  Basically, it is looking at how fast the molecules are moving.  Temperature is the measurement of the molecules' average speed or kinetic energy.  We tend to look at it as hot and cold.  A hot substance has faster-moving molecules.  Those are relative terms.  Heat is the flow of thermal energy from a warmer object to a cooler object.  Heat always moves from one system to another because of a temperature difference.  It is the movement of energy.  It will always move from a higher to a lower temperature.  When you touch a hot surface, thermal energy from the object travels to your hand.  You absorbed thermal energy.  When you touch something cold, thermal energy from you travels to the object.  The object absorbed thermal energy.  

There is no cold.  Cold is the absence of thermal energy.  There will be no energy flow when both systems are at equal temperatures.  We say the systems are at equilibrium. 

Activities to Explore Thermal Energy

Here are some great ways to introduce your students to the study of thermodynamics.

1.  Learn about the molecular movement of molecules by studying the diffusion of food coloring.  When the water is hot, the food coloring will spread faster.  This lets the students see that the molecules are moving.  Available in 4-grade levels.

2.  Practice taking the temperature of different liquids.  Students can place the thermometer in different water temperatures to discover that the warmer the liquid, the higher the temperature.

3.  Explore melting by investigating conduction.  This is a great lab for showing how thermal energy transfers from one object to another.  Place ice cubes on different surfaces and see what melts the fastest.  This lab is easy to prep and can be completed in 30 minutes.

4.  Discover how salt affects the temperature of ice.  I love danging ice on a string.  It is a fun experiment, and the kids begin to understand more about the freezing point of water.  It makes a great science fair project.

5.  Make ice cream with students.  This is always enjoyable and a wonderful way to show a liquid turning into a solid because of the drop in temperature.  

Get the free recipe.

 6.  Explore with dry ice with older students.  Dry ice is a great way to teach about phase changes.  Students can observe the solid going directly to a gas.  Click to learn how to integrate into your class.

7.  Reaction in a bag is another great experiment.  It is a chemical reaction that will release heat or absorb heat.  When it absorbs heat, it feels cold.  A great example of conduction.  Find the directions here.

8.  Explore the freezing point of water using glow sticks, ice, and salt. Great for Halloween, winter, and properties of matter unit. This hands-on experiment is easy to prep, memorable, and can be conducted in 30 minutes. It lets students see that heat is being lost and transferred to the ice.  We recommend integrating it with a science of ice cream unit.

9.  Observe how ice absorbs sunlight and converts it to heat.  This is a fun science and STEM challenge.  Students will build a shade device to protect a popsicle.  Head on over to see all that is included.

Have fun exploring thermodynamics.  The amazing thing is that two materials can be at the same temperature but transfer thermal energy (heat) very differently.

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