A Turning View of Tide Pools
At a beach discovery tent, visitors study drawings of tide pool animals without collecting living animals. The class wants to build a display that slowly turns a cardboard disk covered with drawings. Visitors can watch the drawings move past a viewing window. The device must run without batteries or a wall outlet.
The class has a small solar panel, covered wires, and a slow-turning gear motor from a classroom kit. A solar panel supplies electrical energy when light reaches it. A motor uses electrical energy to turn a small rod called a shaft. An adult helps connect the kit. Students attach the cardboard disk to the shaft. They keep the dry device away from seawater and place a clear guard around its moving parts.
The display has two requirements. The disk must make at least 6 but no more than 10 complete turns in one minute, so visitors have time to see the drawings. The disk must also be no more than 12 centimeters wide to fit behind the viewing window. The clear guard used during testing is large enough to hold every trial disk safely.
The class makes three disks from the same kind of cardboard. Each disk has the same drawings, but the disks have different widths. For each test, students use the same panel, motor, wires, stand, and test location. They test in steady, bright sunlight and count complete turns for one minute. Changing only the disk size helps them compare the designs. After choosing a disk, they plan to investigate what happens when less light reaches the panel.