Wave Tests at the Backyard Tool Shed

A Floating Disk Test

Devin's class visits a backyard to investigate water waves at a low table beside a closed tool shed. An adult sets out a long, clear water tank, a paddle, rulers, and a small foam disk. The tank contains clean tap water. Students keep the floor dry and observe from the sides.

Step 1: The class waits for the water to settle and marks its resting level. A crest is a wave's highest part. A trough is its lowest part. On this sheet, wave height means the vertical distance from a trough to a crest. Crest spacing means the horizontal distance between neighboring crests.

Step 2: The adult moves the paddle to produce each pattern, adjusting the stroke size and rhythm between tests. The class uses the same tank, water depth, disk, and disk starting place. Students wait for an even pattern before measuring. They record wave height in millimeters and crest spacing in centimeters.

Step 3: Students watch five waves pass the disk. A ruler helps them measure the distance between the disk's lowest and highest positions. They repeat each test. Both runs give the same measurements when rounded to the nearest millimeter. They also observe the disk for the same length of time with the paddle still.

Step 4: During Test K, students follow a crest toward the far end of the tank. The disk rises and falls near its starting mark, moving less than 1 cm sideways during the five waves. The class later makes side-view models. Each model shows the surface at one moment, not its motion through time.