Grade 8 Particle Theory Exercise Martin Skoda

Everyone in the class will move like particles while the teacher narrates certain processes. It is meant to have the class experience these definitions and processes in a new way, physically.

Key words can be written on the board as they come up in the exercise. It may be helpful to then stress that these words will show up on a test.

Have the students move as they think particles would move and pose questions to them throughout to make sure they understand what is going on.

1. Pure Substance (key words here are freeze, melt, evaporate, sublimate, condense)

- as a solid, have them so close they are nearly touching, and vibrating

- as a liquid, have them moving about in a medium sized space with elbow room between them

- as a gas, have them move around the entire room with arm lengths between them

2. Split the class up into two groups. Give one group one color of paper (eg. white) and the other group another color (eg. pink). The paper will distinguish the groups and can be used at the same time to take down notes.
3. Have the whites on one side of the room in a crouch with equal space between them (they are water, the solvent). Pinks will be on the other side (they are salt, the solute). Have the pinks move in among the whites, dissolving. They will then also crouch down because a solution appears to be one substance.
4. Now add heat to the solution to boil it. Water will evaporate and collect (condense) on a cool surface (near the black board for example). When we wish to collect the water we call this process a distillation (the water is the distillate and the salt is the residue). When our goal is to collect the salt then we call this a crystallization and the salt we collect are crystals (the water in this case simply evaporates, we don’t need it).
5. Lets create a mechanical mixture now. The whites will be the water and the pinks will be granules of sand. Mix them together in one section of the room. Teacher acts as filter and has the mechanical mixture “pass through” the filter. Water will pass (filtrate) while the sand will be held by the filter (residue).
6. Have the pinks remain as sand and now mix in the whites as pieces of iron. Now use a table as a magnet and have then act out the separation (iron will separate due to the forces of magnetization).
7. Have the class switch roles and go through the exercise again.

The kids may find this exercise weird but that is because they have never moved in science before. To motivate them I would give them a choice to review these concepts with pen and paper or to get up and move. Some of the kids came up to me after the test and said that the exercise helped them remember some things during exam.