Energy systems


6. Troubleshooting a Direct-drive or Friction-drive Car


Students continue working on their direct-drive and/or friction-drive cars. As they do so they note the problems they encounter, then develop and record their troubleshooting strategies.

Advance Preparation

  • Photocopy worksheets: “Direct-drive Car Troubleshooting Guide” and “Friction-drive Car Troubleshooting Guide”. Download below.
  • On chart paper write the headings for a Direct-drive Car (or Friction-drive) Troubleshooting Chart. (See below.)


Same as for Lesson 5: Motors, AA batteries, skewers, straws, wheels, bushings, Aluminum foil, wire, rubber bands, paper fasteners, tape, and cardboard rectangles and strips

  • Partially competed cars from Lesson 5
  • Worksheet for Direct-drive Car Troubleshooting Guide


  1. What is troubleshooting?
    Many of the students’ cars may not be working yet. In a class meeting explore how to address these problems. Ask: If something doesn’t work the way you want it to, what should you do?
    Develop the idea that it doesn’t make sense to start over, because most of what you made is probably OK. Also, if you start over, you might just run into the same issue again! It makes much more sense to:

    • Find out exactly what is preventing it from working, and
    • Then solve only that problem.
      In engineering, this way of addressing issues is called troubleshooting. For suggestions about how to fix a direct-drive, see Troubleshooting section, Lesson 5.
      In Lesson 4, students began compiling lists of issues. In Lesson 6 they make a Troubleshooting Guide.
      Here is how to introduce the Troubleshooting Guide..

  2. Complete a direct-drive-car and a Troubleshooting Guide:
    Students continue to build their direct-drive-cars. They list any issue that arises on the Worksheet, as well as the cause and the fix.


  • To fix a problem, first you have to know what’s causing it.
  • Friction can prevent things from moving, and can be reduced by preventing things from rubbing each other.
  • Electrical connections must be tight for current to flow in a circuit.
  • Mechanical connections must be tight in order to transmit power.
  • Word-wall: mechanical connections, electrical connections.