At Rydal East Elementary School in Abington, Linda Spinella’s 4th grade scientists and engineers were busy conducting tests, collecting and recording data, and thinking about how to analyze results. Using STC’s Motion and Design kit, the class was exploring the concept of stored energy and the variables that affect the speed and distance that their model vehicles could move.

Working in teams of three or four, the students had already built standard vehicles using KNEX® parts provided in the kit; experimented with ways of using force to pull the vehicles; tested their motion while carrying loads; and used rubber bands to supply the energy needed to move their cars. Their task in the current lesson was to predict and investigate how variations in rubber band energy – determined by how many turns they use to wind it up – affected the distance their vehicles travel.

Before tests began, Linda helped the teams get organized. Each person on a team has a number and a job – including reading the directions. One team member collects adding machine and masking tape, another gets the team’s vehicle, and a third collects colored sticker dots to use for recording results.

Linda leads a discussion to review what they’ve already done, how to conduct their tests, and how to record information so they’ll be able to compare results from different vehicles. “Shall we put the sticker where the front wheels stop, or the back wheels?” All teams agree that they’ll mark the stopping point of the front wheels, and that they’ll start all their vehicles the same way – with the front wheels on the starting line.

With each team using four meters of adding machine tape the class needs a lot of space. Fortunately, a lot of space is available –- a former classroom with furniture pushed back, used as a music room and, at the moment, a science lab.

After taping their adding machine "tracks" to the floor, teams mark their starting line with masking tape and wind the rubber band two turns. One group explains their technique for keeping track of the number of turns: count each time they see the end of the rubber band. Before releasing their car, they predict how far it will travel.

Students base their predictions on their prior experience and on how the rubber band feels, noticing that it gets tighter with each turn, storing more energy. They mark their predictions on the tape.

Each team decides how members will divide the work. Operating the cars, measuring, and recording are all key tasks in this investigation. Later they will share results, identify patterns, and discuss relationships they find.

As teams work independently, Linda observes, listens, encourages, and helps students trouble shoot. In the case of widely discrepant results, she asks, “Which do you think is wrong?” Noticing careful recording, she comments “I like that you remembered your units.”

As patterns emerge from their data, students realize that the cars go more than twice as far with twice as many turns. Their observations help them begin to explain why: When the rubber band is wound tighter, the car keeps going even after it’s completely unwound.

An eight-minute warning gives groups time to finish tests and head back to the classroom, carefully rolling up the adding machine tape which can be used as a huge graph on the wall. In the coming weeks, they will continue to use their vehicles to study the effects of friction and wind resistance, sails and propellers. At the end of the unit, a final design challenge offers a chance to apply all that they’ve learned about technological design and the physics of motion. KSN staff thoroughly enjoyed watching these investigators in action. Many thanks to Linda and her students for the opportunity, and congratulations for the hard work and serious science learning going on in a setting that was clearly so much fun.