Step 1: Materials
Step 2: Pyramid Frame
Fold the shape into a triangle and connect the ends together.
Peel off a length of tape from the roll without severing it. Wrap the entire perimeter triangle in tape as you peel it off of the roll.
Repeat 2 more times to create a total of three triangles. Arrange them in a trapezoid pattern and tape the edges together in at least two places.
Fold the outer two triangles upwards to form the pyramid. Tape the edge together to keep the pyramid shape intact.
Step 3: Catapult Arm
Insert the pointed end of the three middle skewers into the remaining 1/2 straw piece. Tape it on.
Lay the skewer bundle inside the catapult and align the straw with the front of the pyramid. Tape the straw to the front edge of the pyramid. This will create a flexible joint which will allow the catapult arm to move up and down.
Attaching the arm to the catapult frame requires a lot of dexterity. Encourage your students to take turns helping each other with this step: one person holds the pieces in place while the other tapes it.
Step 4: Rubberband
Step 5: Attach the Cup
Step 6: Fire!
Step 7: Advanced Ideas: Collapsible Catapult
Click on the images to read the design notes.
Step 8: Safety, Tips, and Troubleshooting
- If students are having trouble launching their catapult, be sure that they have a little bit of skewer exposed at the top of the arm and that they are launching according to the technique displayed in step 6. It is difficult to launch by grasping the cup or pushing on the middle of the catapult arm.
- Some students may have difficulty forming the pyramid shape. Encourage students to work together: one person holds the shape in place while another person tapes it together.
- Attaching the rubber band can be tricky for some students. You may offer to do this part yourself.
- If the catapult arm is wobbly, check to make sure that the end is securely taped to the bottom front of the catapult
- If the cup is wobbly, encourage the student to apply more tape around all sides and around the catapult arm.