Hinge: Something that connects two objects and lets them rotate.
Pivot: The pin on which a mechanism turns
Force: The push or pull on an object
Scissor Mechanism: Two straight bars that are connected to each other at their intermediate points by a joint
Lever: Rigid bar resting on a pivot
Target Audience Minimum Age
Target Audience Maximum Age
Duration in Minutes
As a result of participating in the program, participants will understand the mechanics of a simple hinge and how to manufacture one.
2 milkshake straws (10 mm)- $0.12
9 craft sticks- $0.30
8 toothpicks $0.04
1 foot tape- $0.02
Optional “Finger” Materials:
Hot glue gun/sticks
Cup or bowl
Pom poms or beads
Materials/Costs in $
Prep Time in Minutes
Optional: Precut the straws into 2 inch pieces
After building their grabber and designing the "fingers," students may test their grabbers by picking up small objects (like pom poms) and moving them into a cup or bowl.
Creating the Scissor Mechanisms
Cut straws into 8 pieces 2" long each
Create 4 levers by inserting craft sticks into each end of 4 pieces of straw
Reinforce the straws by taping a toothpick to the side of each
Overlap two levers at the straws and push a toothpick through the straws to create a scissor mechanism (looks like an X.) Add two more pieces of straw to the top of the X.
Repeat with the other levers.
Turn the scissor mechanisms (Xs) so the top straws are facing each other. Use toothpicks to connect the top straws to each other. Repeat with the bottom straws.
Designing the "Fingers"
Students may now design their "fingers" for grabbing using any extra materials. I recommend first attaching half of your 9th craft stick to each end using hot glue, then adding on "grippers" of your choice. See the photo tutorial or the instructable for ideas.