Rubber Band Cars

There's something powerful about physically making something that works yourself. The tinkering, trial and error testing, and early frustration often lead to some impressive feelings of accomplishment in the end.

This year when covering the types of energy and energy transformations, I realized a project I ran for 6 years at my school in Michigan would fit in quite well: The Rubber Band Car Project.1

You can check out the handout and guidelines I provided to students, though the basic gist of the project consists of:

  • Building a car from found materials;
  • Using no more than two #33 size rubber bands to power the car;
  • Getting said car to move as great a distance as possible (6 meters is the goal);
  • Describing how the energy stored in the rubber bands is transformed and conserved as the car does its thing.

Testing Rubber Band CarsInitially students are generally pretty worried because the guidelines ban items like CDs & DVDs as wheels, and Legos or other such objects from being used. However, as I share some examples of cars from the past (see them here), and as students start tinkering and sharing ideas with each other, the worries start to fade.

Most of the building process takes place at home, but I provide one day in class for students to bring in their cars (or materials that will eventually become their cars) and work on them in class. This is often extremely helpful for students who are struggling to figure out how to put their cars together and get them to work. As they walk around the room, they can see how everyone else is tackling similar problems and get ideas for how to solve their own.


Standards-Based Grading. I had a pretty solid assessment system that I was quite happy with before I went all-SBG. I'm not sure I'm quite as comfortable with how I'm assessing it using the SBG system. As of right now I'm not too worried by this. The old system had many years of tweaks and adjustments to get it to that sweet spot, and it'll probably take a couple tweaks to get the SBG-assessment for the project there too.

"I didn't do it." In the past there was always a small minority (~2% to 5%) of students who just didn't make anything for the project. This year it seems like the percentage of students with no car will be higher. I'm not sure what to think of that, but it's worrying.

Cool stuff

Non-competitiveness. I try my hardest to make sure the assessment system and the general classroom environment is as non-competitive as possible for this project. I want students to share ideas and collaborate with each other even though they're all making cars individually. For the most part this works out. Students who've figured things out are generally happy to share their knowledge with students who don't. However, there's no getting away from the fact that most students want the bragging rights for having the car that went the furthest.

Engaging the unengaged. Having to physically make something that works is a different sort of project for many students. It's interesting to see how some of the "I-need-an-A-or-I'll-die" students struggle with the project while some who often struggle with traditional projects become the super stars.

Results. I've always recorded every students' results and shared who had some of the most successful cars,2 and this year I'll be using a self-sorting Google Spreadsheet to automatically post the results to the Rubber Band Car Project Page in near real-time.3 I'm not sure if that's really necessary, but it is a fun trick. Perhaps I'll have to do a post on creating self-sorting spreadsheets if anyone is into that sort of thing.


  1. A big tip o' the hat to Mr. Randy Commeret at Grand Rapids Christian High School; from whom I grabbed this project from nearly wholesale. Rumor has it this project has been around for 20ish years in total.    (back)
  2. Which might feed the competitive nature that I'm trying to avoid, but to date it hasn't gotten too competitive between students.     (back)
  3. Which means you can follow along with the results as we test cars on Thursday, March 24 & Friday, March 25. 🙂      (back)