Diffraction-Grating Rainbow

1. Diffraction-Grating Rainbow Materials: Diffraction grating glasses/sheet; white LED source What you do: View a narrow white light through grating. What students see: Multiple spectra appear on both sides. Question: How is this rainbow different from a prism rainbow? 2. Oobleck Dances on a Speaker Materials: Protected speaker/vibration plate; oobleck; tray What you do: Drive low-frequency sound under a thin oobleck layer. What students see: Oobleck forms moving fingers/blobs. Question: Why does sound make a liquid stand up? 3. Pendulum Wave Materials: Pendulum-wave frame or several strings of slightly different lengths What you do: Release all pendulums together. What students see: The row forms changing wave patterns. Question: Why do the pendulums stop moving together?

Predict → observe three demonstrations → compare what changed → choose independent activity station → cleanup/share. Guiding questions: Question: How is this rainbow different from a prism rainbow? Question: Why does sound make a liquid stand up? Question: Why do the pendulums stop moving together?