Learning from home? Find hands-on activities perfect for distance learning. Browse now!

Sprinkle: Spool Racer Design & Competition (for Informal Learning) (en español)

Quick Look

Grade Level: Elementary school

Time Required: 1 hour

Expendable Cost/Group: US $1.00

Group Size: 2

Subject Areas: Physical Science, Physics, Science and Technology

Bolded words are vocabulary and concepts to highlight with students during the activity.

Students see how potential energy (stored energy) can be converted into kinetic energy (motion). Acting as engineers designing vehicles, they use rubber bands, pencils and spools to explore how elastic potential energy from twisted rubber bands can roll the spools. They brainstorm, prototype, modify, test and redesign variations to the basic spool racer design in order to meet different design criteria, ultimately facing off in a race competition.

A photograph shows a pencil attached to a spool by a rubber band that goes around the pencil and through the center of the spool.
Figure 1. A spool racer made from a pencil, rubber band and spool.
Copyright © 2016 Victoria Lanaghan, ITL Program, College of Engineering, University of Colorado Boulder


Each group needs:

  • 1 wooden or plastic spool
  • 2-3 rubber bands of various sizes
  • 2 metal washers
  • 1 toothpick or paperclip
  • tape (masking, duct or clear)
  • 1 pencil



These easy-to-make devices store potential energy in twisted rubber bands and then convert the potential energy to kinetic energy upon release. Students use simple materials to create racers and alter their designs to achieve different outputs for speed and distance.


  1. Organize the students up into groups of two.
  2. Introduce the concepts of kinetic and potential energy; explain that they will build a device that converts potential energy (from the twisted rubber band) to kinetic energy (the spinning spool).
  3. Show students Figure 1 and explain that the goal is to design a racer that travels as far as possible.
  4. To create the basic spool racer shown in Figure 1, direct students to:
  • Use a toothpick (or paperclip) to push a rubber band through the spool hole.
  • Secure the rubber band at one end by slipping the toothpick through the loop, pulling the rubber band tight from the other side, and taping the toothpick and the rubber band loop it holds to the spool end. As necessary, break off some of the toothpick to make sure it does not stick out past the edge of the spool.
  • On the opposite side of the spool, thread a washer onto the rubber band. Then, slide a pencil through the rubber band loop that comes out of the washer.
  • Holding the spool in one hand, spin the pencil around many times, twisting the rubber band inside the spool.
  • Set the spool and pencil on the floor (tile is best); then release it. Vroom, vroom!
  • After racers have been built and tested, have groups go through the design process (design-build-test) several times in order to make a better spool racer. Suggest they creatively experiment with different-sized rubber bands, different numbers of spins, two pencils, etc.
  1. To conclude, have students demonstrate their best racers to the rest of the class. If time permits, have a class competition.

Wrap Up - Thought Questions

  • What worked well about your design? Why?
  • What did not work well? Why not?


© 2016 by Regents of the University of Colorado

Last modified: June 10, 2020

User Comments & Tips

Free K-12 standards-aligned STEM curriculum for educators everywhere.
Find more at TeachEngineering.org