Science Students: Start your engines!

"When I pull out the constant velocity cars, I usually hear a chorus of, 'All right!' from the class. That's what I think, too, because these powerful miniature dune buggies are so effective at helping my students really grasp what constant motion is and how to graph it. They get immediate kinesthetic and visual feedback, and I get the satisfaction of making a solid lesson super fun." – Mark Davids

Constant Velocity Demonstration

You'll need paper strips, markers, plus a constant velocity car and a metronome that beeps. Have students lay out paper strips to form a "road" for the car. Explain that they'll start the car, then mark its position at each beep of the metronome.

Start the metronome and have students start their cars. They will clearly see that the marks are equally spaced. Have them predict how the marks would fall with a faster car, and then have them check by increasing the speed of the car.

Have students graph the position vs. time results and they'll see nice, smooth curves that suggest the slope of the graph represents a constant velocity. They can also run the cars in the opposite direction — and discover that negative velocity produces a negative slope when graphed.

Mark Davids is a Presidential Award winner and recipient of the Excellence in Pre-College Physics Teaching Award, Mark has been teaching students and teachers for more than 37 years. He has written curricula, content standards and served as a grant reviewer, along with presenting at local, state and national conferences.