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Solid, Liquid, Gas!

Students explore atom interactions in different states of matter with this physical game.

All matter is made out of tiny particles, those particles can be single atoms or groups called molecules. For example, water is made out of two hydrogen atoms and one oxygen atom, forming a molecule called H2O.

Water has many different states such as solid (ice), liquid (water), and gas (water vapour). When the particles come close together and have little energy, they stick to each other in a regular arrangement and vibrate slightly, forming a solid. Particles in liquids are still tightly packed, but they have enough energy to roll over each other. In a gas the particles are no longer packed in as they have enough energy to fly around in all directions quickly.


  • Describe the properties of a solid, a liquid, and a gas.


  • Large space for students to run around

Key Questions

  • Why would it be easier to cut through gas than solid?
  • Why does gas and liquid take the shape of its container and a solid doesn’t?

What To Do

Students represent the smallest particle (an atom or molecule depending on the substance).

  1. When facilitator yells “Solid!”, students (particles) must run together, form a grid pattern and walk on the spot.
  2. When facilitator yells “Liquid!”, students must walk around reach other but still be quite close.
  3. When facilitator yells “Gas!”, students must run as far away from each other as possible.

Consider marking out a ‘bowl’ outline. Solid students will form a shape resting in the bowl but irrespective of its shape. Liquid students will fill the bowl. Gas students will fly out of the bowl.


  • Demonstrate how tightly packed atoms are by having a kid be a “knife”. Can he/she run through atoms in a solid as easily as a gas?When do students represent atoms (metals) and molecules (non-metals and compounds)? Why? How could this model be changed so that students represent atoms even when demonstrating a molecular substance?Are particles attracted to each other? What is the evidence for and against this? How can the attraction be broken? Is this physical or chemical change?