Third graders in Grace Crowell’s science classes have been learning about the properties of magnetism. Students worked in teams to build magnetic race cars on the final morning before Winter Break. They raced them against each other on a hand-drawn paper track to see which team could successfully use the magnetic forces of attraction and repulsion to maneuver their car down the track and across the finish line.
Grace gave each team four bottle caps for wheels, two toothpick axels, pieces of drinking straw, and a AA battery. While the car’s design was simple, some groups discovered through experimentation that the bottle caps rolled more smoothly when the open side of the cap faced inward. After using hot glue to assemble their vehicle, students worked in groups to take a few practice runs and collaborated to find the best technique to guide their magnet car down the track as quickly as possible.
For the first race, the “driver” in each group used the attraction between a charged magnetic wand and the positive pole of the car’s battery to pull the car down the track. The cars moved quickly and were easy to control as the wand guided the vehicle’s direction. Then Grace switched up the wands and challenged her students to place the wand behind the car and try to “repel” it down the track as quickly as possible. This race was far more difficult as the cars were harder to control from behind and swerved around the track. Each team had to help their driver problem-solve by reorienting the magnet to maneuver the car most effectively and then cheered as the vehicles crossed the finish line.