Diffraction-Grating Rainbow
Multiple spectra appear on both sides.
Teaching & key ideas
What you do: View a narrow white light through grating.
What students see: Multiple spectra appear on both sides.
Why it works: Closely spaced lines make different wavelengths interfere at different angles.
Question to ask: How is this rainbow different from a prism rainbow?
Lesson flow
Predict → demonstrate → observe → briefly explain → ask: How is this rainbow different from a prism rainbow?