Introduction (5 minutes)
Hi Charlee! Remember reading "Keep It Simple, Randel!"? That book showed how characters in fairy tales used simple machines, sometimes without even realizing it! Can you recall any simple machines Randel or other characters used? (Examples: lever, pulley, inclined plane, wheel and axle, wedge, screw). Today, we're going to focus on one of those – the lever – and build our own simple machine, just like a fairy tale inventor!
Activity: Build a Lever Catapult! (25-35 minutes)
We're building a catapult, which is a type of lever. A lever helps us move things more easily. It has a stiff bar (our craft sticks), a pivot point called a fulcrum (our box/books), the force we apply (effort), and the object we want to move (the load - our marshmallow!).
- Create the Lever Arm: Stack about 7-8 craft sticks together. Use two rubber bands to tightly secure them together at both ends.
- Create the Fulcrum Base: Stack 2-3 craft sticks. Slide this small stack between the bottom stick and the rest of the main stack, about one-third of the way from one end. This small stack acts like a spacer and helps create the pivot. You might need tape to hold this spacer stack in place on the bottom stick if it slides too easily.
- Attach the Spoon: Place the plastic spoon on top of the main craft stick stack, with the handle pointing towards the closer end (the end with the smaller gap created by the spacer). Secure the end of the spoon handle to the top craft stick using another rubber band. Wrap it tightly!
- Set Up Your Catapult: Place your cardboard box or stack of books on your workspace. This will be your fulcrum base. Rest the craft stick lever arm across it, positioning the spacer stack directly over the edge of the box/books.
- Test Fire!: Place your soft object (marshmallow/pompom) in the bowl of the spoon. Gently press down on the spoon end of the lever. Let go quickly! See how far your object flies.
- Experiment: Try moving the lever arm forward or backward on the fulcrum base. Does changing the position of the fulcrum change how far the object goes? Why do you think that happens?
Wrap-up (5 minutes)
Great job building your lever catapult! You've just used physics, like Randel! What did you observe when you moved the fulcrum? Changing the fulcrum position changes how much force is needed and how far the load travels. Think about where else you see levers used – maybe a seesaw, scissors, or even your own arm!