Science Lesson Plan: States of Matter

Before I had kids of my own, I spent a summer as a science camp teacher. I loved doing hands-on activities with children to teach them about science. Some of the parents jokingly called our science camp "toy camp" because most of our science lessons had some sort of hands-on toy that we gave the children which was associated with the concept of the day. That's the great thing about science. We can find science experiments all around us--even in our toys--it isn't just some boring thing we read about in textbooks. 

Later, after I was no longer teaching summer camp, some of my friends who were teaching their children at home asked me to be a "guest teacher" for their preschool and kindergarten age kids. So I adapted one of my lessons about states of matter for the children. This lesson was a big hit with the kids.

States of Matter Lesson Plan

(1) Students will be able to identify the difference between solids, liquids, and gases.
(2) Students will be able to understand that matter can change from one state to another.

Key Terms:
  • matter
  • molecule
  • solid
  • liquid
  • gas
Materials Needed:
  • magnifying glass
  • random small objects to observe
  • containers with solids, liquids, and gases
  • test tube
  • balloon
  • baking soda
  • vinegar
  • diet coke
  • mentos
  • handouts
  • scissors
  • crayons
  • glue
Lesson Activities:

Matter and Molecules

First, I introduced the term "matter." I taught the students that matter is all of the "stuff" around us. I had students take turns pointing to matter that they saw in the room.

Then I introduced the idea of molecules. I had the kids look at a few items of matter through a magnifying glass and see if they could notice anything different looking at the items closely. Some things you don't notice about objects until you look at them with a magnifying glass. Molecules are so small that we can't see them even with a magnifying glass but they are still there. Everything around us is made out of tiny invisible molecules.

States of Matter

Next, I taught the different types of matter. I did a human demonstration in which the kids became the molecules. First I had them stand close together making a wall. I had them stay still, and I showed them how I couldn't get through their wall. I explained to them that they were acting like a solid. We defined a solid and identified other solids in the room. Next I had them spread a little bit apart. They were allowed to move a little, but not very much. I showed them how I could "swim" through them because they were acting like a liquid. We defined a liquid and identified liquids in the room. Finally, they became gas molecules. They loved spreading out and running around. I showed them how easy it was for me to run in between them. We defined a gas.

To test their knowledge I pulled out containers with different objects. I had old baby food containers that I filled with random liquids and solids. I also had one empty container to represent gas. I let the kids take turns choosing a container. Each child opened the container and got to examine the object inside. Then, I quizzed them on whether that object was a solid, liquid, or gas.

Changing Matter

I introduced the idea of changing matter by talking about super heroes. Super heroes have many different talents--some can fly, some can turn invisible, some have super strength. We get to be super heroes today by becoming matter changers (just like Frozone in The Incredibles). I had the kids chant "1-2-3 Matter changers!" with me.

I then taught students about how matter can change from one form to another. I explained the example of an water, ice, and steam. We talked about how when we are cold we like to cuddle up in blankets to get warm. But when we are hot, we like to run around and have fun. Molecules are the same way. When they get cold, they get closer together. When they get hot, they spread apart. When can change matter by making it hot or cold.

I then told students that we can change matter in other ways. Sometimes when you mix two different things you can make a new thing--like when you bake cookies. You can do that with matter. You can take two kinds of matter and turn them into a different kind of matter.

I pulled out the balloon, baking soda, vinegar, and test tube. I had the students look at each item and decide whether the item was a solid, liquid, or gas. Then, once they had observed the baking soda and vinegar, I used a funnel to pour some baking soda into the balloon and some vinegar into the test tube. Then I attached the balloon to the test tube. We did our chant "1-2-3 Matter Changers!" and I lifted up the balloon to allow the baking soda to drop inside and mix with the vinegar. The reaction of the baking soda and vinegar caused the balloon to inflate on its own. I explained to the students that the solid and liquid had created a gas that was now filling the balloon. A video of my preschool aged boys doing this demonstration is below:

Playing with Matter

For our finale, I took the kids outside to play some more with matter. On the way out, we identified solids, liquids, and gases around us. Then, I pulled out the materials for our last experiment. I had a bottle of diet coke a pack of mentos. I also used the special test tube below:
I had students identify states of matter one more time. I explained that the diet coke actually had both a liquid and a gas in it. The bubbles were the gas. I had the kids guess what they thought would happen if I mixed the solid mentos with the liquid soda and gas bubbles. Then, we loaded a pack of mentos in my test tube and dropped the mentos into the soda. The kids loved watching the diet coke geyser shoot up in the air. I explained to them what had happened. When we dropped the mentos in, the gas bubbles all stuck to the mentos. Because the gas bubbles were jumping around taking up so much space, there wasn't enough space for the liquid in the bottle anymore. So the liquid was pushed out into a fountain. After the explanation, we tried the experiment one more time.

And just in case, you've never seen this demonstration before, here's a classic video of diet coke and mentos geysers in action.


For a review activity, I had students color a solid, liquid, gas handout that I had made. Then they they found pictures of items that represented each state of matter and glued them on top of the corresponding state of matter. I had some clipart of several items I had found from searching online already printed for the kids to sort. You could also have them look through magazines or advertisements for items to fit into each category.

Some examples of pictures of items that would fit each category:

Liquid: juice, water, soup, soda
Solid: car, apple, watch
Gas: wind, steam, bubbles

Below is an image of the States of Matter handout I created that you could print out to go with this activity:

We had a lot of fun experimenting with solids, liquids, and gases. For more ideas for teaching your kids about science, check out my Science Pinterest Board.


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