Description: Design and build a moving machine using a rack and pinion gear mechanism. After visualizing the motion of the machine, children sketch ideas, and then build the rising and falling scene. Ideas may include animals, flowers, rockets, airplanes, and/or other creations.
Learning Targets: Gain more experience and confidence using basic crafting tools, including the use of a servo motor. Participate in design-oriented projects that have no predetermined outcome with open narrative, creativity and expression.
Grade Band: 4th – 7th
Age Range: 8-12 years old
Prep Time: 30 minutes
Learning Time: 90 minutes
- Glue gun + glue sticks
- Cutting knife + mat
- Lollipop sticks or bbq skewers
- Cellophane tape
- Masking tape
Scrap cardboard pieces
Colored craft paper
- FoldMecha rack and pinion gears (precut on laser cutter) for a continuous servo or a 180-degree servo.
- Hobby servo motor (1 per student project)
- PaperMech paper placemat: 11×17 placemat or 8.5 x 11 placemat.
- Rack & pinion tutorials: [Continuous servo video][180-degree servo video]
10 min – Imagine. Set placemats at each place setting, one per child. Ask them to sketch, plan, and draw their ideas. Review instructions on how to build an up-down rack & pinion mechanism. Help children get started by asking them what are their interests, their favorite animal, storybook character to help brainstorm what to include in their design.
45 min – Make & Test. Pass out one set of materials per project. Help students name the parts and their purposes – a servo motor, a microcontroller, or gears. Have students start assembling their rack and pinion mechanism. Remind students to test their mechanism’s motion with a microcontroller to troubleshoot any motion problems before decorating it.
30 min – Decorate & Write. Set craft materials at a separate table. Invite students to decorate their mechanisms only after they have tested their movements. Ask students who finish early to write an exhibit label description on a card.
10 min – Share & Reflect. Ask students to test their machines to see it moves as expected. Showcase their creations. Invite children to share what inspired them to make their machine; what were challenges they faced and how did they overcome them; what might they change or do differently if they had more time.
“Circular into Rectilinear Motion (or vice versa) by means of rack and pinion.” 507 Mechanical Movements. Mechanism #113.
“Stamp. Vertical percussive falls derived from horizontal rotating shaft. The mutilated toothed pinion acts upon the rack to raise the rod until its teeth leave the rack and allow the rod to fall.” 507 Mechanical Movements. Mechanism #351.