Snail car

Challenge

Use gears to make a motorized car that moves as slowly as possible.

Here are the rules:

  1. Your snail must include a power source such as an EV3 brick or WeDo hub, one or two motors, and one or more gear trains. You may also use craft materials, such as pipe cleaners and tissue paper, for decoration.
  2. Your snail must move forward at a constant pace during the race, though its forward motion can be very slow. In other words, no stopping, no turning, and no backing up.
  3. You must calculate the slowdown of your snail–how many times the motor must turn for the wheels to turn once.

Materials

  • LEGO pieces for building a motorized one-motor or two-motor car.
  • Additional LEGO beams and gears for gear trains
  • Craft materials for decorating snails
  • Masking tape for starting line

Notes for the teacher

  • This activity can be done using MINDSTORMS EV3 or NXT, WeDo, BOOST, or Power Functions motors and battery packs.
  • Before doing this activity, be sure that the students are introduced to gear trains. Depending on the age of the students and the amount of time you wish to devote to this activity, you may want to introduce compound gears and worm gears as well.
  • If you do not have access to a large supply of gears, you may want to set limits on how many gears each group may use.
  • You may want to add an additional constraint that the students must demonstrate that their snail moves forward, at least in theory, rather than moving backward (a real possibility, if the gear trains are complex).
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Barbara Bratzel

Barbara Bratzel

Barbara teaches at the Shady Hill School in Cambridge, Massachusetts and works at the Center for Engineering and Education Outreach at Tufts University. She is the author of several LEGO robotics activity books for teachers, most recently STEM by Design.
Barbara Bratzel

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