- Use a hands-on approach to explore and comprehend basic concepts in engineering and physics like stored energy, trajectory, reinforcement, density, levers and hinges, and trusses.
- Acquire an understanding of the different parts of a catapult: the base, the support structure, the arm, and the basket.
- Strengthen critical thinking and motor skills as they build their siege engines and troubleshoot any design flaws that may arise.
Prep work: 2/5
Setup time: 2/5
Each mini siege engine is built differently, so I will outline how to build the individual models in the following steps. For now, let's focus on what these little war machines have in common:
Trusses: I explain to the students what a truss is and why it's so strong and useful. Trusses are basically triangles that are used to strengthen a structure. Trusses do not change their shape easily, unlike squares which can flatten into rhombuses (sometimes I will make a triangle and a square out of craft sticks and show the students how easy it is to squash a square, but not a triangle). Trusses also require very little materials which makes them highly efficient. The catapult in the photo above uses trusses to support the downward pull of the catapult arm. If the trusses were replaced with a pair of beams perpendicular to the base, the whole support structure would collapse if the arm were to be pulled down.
Reinforce: This is easy to explain - reinforce simply means adding more material to make something stronger, like gluing sticks on all sides of the base instead of just one.
Trajectory: I explain that trajectory is the path that an object, or projectile follows through the air. What happens when the projectile is aimed upward at 45 degrees? The trajectory it takes will be a nice smooth arc. Aimed straight forward? Immediately begins to fall toward the ground. ( Just like in Angry Birds - kids can really relate to this!) Changing the trajectory will change how the projectile moves. Most kids understand this intuitively.