States of matter: An introduction

Matter is defined as “that which occupies space and possesses mass.”

Matter exists in three primary states: solids, liquids, and gasses. (There is a fourth state of matter, plasma, but we did not cover plasma during our states of matter unit.)

In this post I share how I provided my kids with a very basic introduction to states of matter.

Note: For more activities about matter, please see my states of matter unit study page.

Following the recommendations in my Montessori physical science manual, my initial introduction to states of matter started with the preparation of a matter tray.

This was just a simple tray with three sections.

I labeled the first section “solid” and put a rock inside.

I labeled the second section “liquid” and put a container of water inside.

I labeled the third section “gas” and put a container of gas (i.e., empty except for air) inside.

On the morning I began introducing matter to my kids, I pulled out this tray. I first defined matter as anything that takes up space or as anything you can touch physically.

I then explained that all matter occurs in one of three states or forms: solids, liquids, and gasses. I then showed them the three objects in the matter tray and labeled each as solid, liquid, or gas.

During the next lesson, I presented the liquids tray. This tray included several containers filled with water, as well as a label that said “liquid.”  In sharing this tray with the kids, I used the opportunity to explain that liquids:

• do not have a definite shape, but take the shape of their container
• have a definite volume
• have a definite mass

We talked about how liquids change shape when they move from one container to another. To illustrate this, I let my kids pour water from one container to another.

We also talked about what would happen if we were to pour the water onto the table. We all agreed it would begin to spill on the floor and we would need to get a towel to wipe it up! I even demonstrated this by spilling some water, much to my kids delight!

During the next lesson on matter, I presented the solids tray. This tray included several solid objects as well as the label “solids.” In sharing this tray with the kids, I used the opportunity to explain that liquids:

• have a definite shape
• have a definite volume
• have a definite mass

To illustrate the properties of solids, I allowed the kids to hold the various objects. We talked about how solids have a definite shape. We all agreed that if we were to drop one of the solid objects on the table, we would not need to get a towel to wipe it up as we had to do for the water.

We also talked about how solids have a definite shape, but the shape can be changed if enough force is applied. For example, the pipe cleaner on the tray pictured below is a solid, but my kids could bend it if they tried. (On a different day I made the same point with play dough, explaining how play dough is a solid and has a definite shape, but that we can change its shape if we apply enough force to it.)

During the next lesson on matter, I presented the gasses tray. This tray included a straw, bubbles, and balloon as well as the label “gasses.” In sharing this tray with the kids, I used the opportunity to explain that gasses:

• do not have a definite shape
• do not have a definite volume
• have a definite mass

Of all the types of matter, gas is definitely the most difficult to teach about because it is the most abstract. For the most part, we cannot see gas. We rarely feel gas. So the purpose of this tray was to make the concept of gas as concrete as I could for the kids.

We used the straw the blow into. We took turns feeling the air coming out the other end of the straw. We blew up the balloon and talked about how the balloon got bigger because it filled with air/gas. Lastly, we blew bubbles and talked about how each bubble was formed by blowing air/gas.

More resources for learning about states of matter

More states of matter posts from Gift of Curiosity:

• Books about states of matter
• Exploring states of matter with water, ice, and steam
• Balloon magic with baking soda
• Dancing raisins science demonstration
• Melting candle wax to explore states of matter
• Exploring air pressure