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Lesson Plan

States of Matter and State Changes

Define solid, liquid and gas. Use water to show state changes. End with a snack made through state changes.
Science content (2016 curriculum): 
Chemistry: States of Matter, Properties of Materials (K-7)
Chemistry: Physical Changes, Solutions, Mixtures and Separating (2, 4, 5, 6)

If including the frost activity, set up frost cans in the centre of each table group at the start of the lesson. (They will be used as part of the state changes in water activity.)

Introduce or review the concept of solid, liquid and gas:
Solids: fixed size and shape
Liquids: change shape to fit their container but has a fixed size so takes up the same amount of space as it flows
Gases: change shape and size to fill their container
Either ask students to point to examples the classroom, or do the states of matter scavenger hunt.
[Some students may also point out that plasma is also a state of matter, which it is. The sun contains plasma.]
Optional: book on states of matter: “Matter” First Fact book (Capstone Press)

Introduce that everything is made up of tiny tiny particles, too small to see. (An atom is 10-10m, or 10 million in a dot a mm wide.)
In a solid the particles are packed close together, that is why a solid feels hard. In a liquid they are further apart. In a gas they are far enough apart that we can move through them easily - move your hand through the air and the wind you feel on your hand is the molecules bumping into your hand.
Useful videos to show the particles in the different states:
Image of particles:
1 minute video of the particles in solids, liquids, gases:
Longer cartoon video of the particles in solids, liquids, gases at

Act out the states of matter to model what the particles are doing in each case.

Look at state changes in water, including the ice formed on the cans.
Optional: as part of this activity measure the temperature of water in the different states of matter.

End with a snack that exploits state changes:
Popcorn and skits, or ice cream.


Doing all the activities is a long lesson. Exclude scavenger hunt for older students. Exclude measuring the temperature of water for younger students. Acting out states of matter could also go, but gets the point across very well.
Lord Roberts: States of matter in water (only solid to liquid to gas), acting out states of matter, popcorn, ice cream.

Grades taught: 
Gr 1
Gr 2
Gr 3
Gr 4
Gr 5
Anke Barabulea
Sonia Ko
Sonja Watson
Taryn Jang
Teaching Site: 
General Gordon Elementary
Laurier Elementary
Lord Roberts Elementary
Lesson plan originally developed and delivered: 

Gordon Elementary. Notes with Laurier Elementary.