Introduction to gas pressure:
The air is made of gas. Many many tiny particles, too small to see, bumping each other and the walls.
If we squeeze some gas particles into a balloon, they are still bumping around, but as there are more of them, they bump the sides of the balloon, and push against it - that is pressure - the pushing. If we blow the balloon up too much, the pressure is too much for the balloon and it bursts.
The pressure also makes popcorn pop.
Make popcorn (or start earlier if it takes a while).
Optional: draw popped and un-popped kernels.
Show slow-motion popcorn-popping video to each table, and check drawings.
Ask students why the popcorn pops - prompt if needed that popcorn contains water that is heated to a gas... which expands... and puts pressure on the husk of the kernal... until it pops.
We will now use gas pressure to make a toy.
Show how to make a stomp rocket.
Draw your rocket and launcher, showing with arrows and words where the gas pressure is created, and where it travels to shoot the rocket.
Optional: add fins decorate rocket.