Today Mrs. Hahn's class earned extra science time. They chose to do some rocket fun. The first one that they watched was a tea bag "rocket". We took a tea bag and cut of the string and emptied out the tea. That left us with a cylinder of light weight paper. We lit the paper and watched what would happened. You can watch the video below. The flame created by burning the tea bag heated the air inside the cylinder. This made the air less dense and it rose above the cooler, more dense air. When the tea bag burned it left behind ash that was light enough that it did not need much force to lift it. It also had so little mass that it floated back down slowly.
Then we took it out side. After much fixing, we finally got the water bottle rocket launcher working. We talked about how the air pressure was built up by the bicycle pump and it wanted to be released. By releasing the ring that held the bottle on to the launcher, the air pushed the bottle several yards into the air. Bonus, the kids got to see me and Will get soaking wet from the last rocket.
Elementary School Science Lab Teacher