My library has been exploring a series of children's events that we named S.T.R.E.A.M. (Science, Technology, Reading, Engineering, Arts, and Math). Our attempt to bring more STEM programming to the library. Recently I taught a basic introductory class about catapults and trajectory.
I started off with the children gathered around me explaining the science used in catapults. It was a great give and take conversation with the small group, as I stopped to ask the meaning of some of the larger words. (I did try to show a Bill Nye explanation video from YouTube but the wifi was not working so I had to skip this short clip.)
Science explanation:
Catapults have been used since Ancient Greece through modern times. They were originally invented to hurl things farther than a human could and made great siege weapons.
Catapults are great for demonstrating transfer of energy. It is a device used to hurl an object. It uses a simple machine called a lever (the spoon and craft stick), which is attached to a stationary point called a fulcrum (the sticks going the other way), to help move a load (the marshmallow or other projectile).
When you pull back on the lever, potential energy is stored. When you let go, the potential energy is transferred to the lever and turned into kinetic energy (the energy of motion), and the marshmallow is flung forward.
Next, I showed the children how to build a simple catapult using 9 craft sticks and rubber bands. The children had a choice of using a plastic spoon or bottle cap on their catapults. I also handed out paper directions in case they forgot a step. I even put out color pens for the children to decorate their catapults if they wished to do so.
When the catapults were built I gave the children marshmallows and pom-poms to use as projectiles. I also gave them sheets of aluminum foil to ball up into projectiles. As suggested on the LibraryLand blog, I created targets on the floor and walls with masking tape.
Reflection - This was a pretty easy program to put together. I already had most of the supplies on hand. While we didn't have a large turn out, the children who showed up had a good time.
