Afterimage Flag
Complementary colors appear as an afterimage.
Teaching & key ideas
What you do: Stare briefly at image, then look at white space.
What students see: Complementary colors appear as an afterimage.
Why it works: Photoreceptors adapt and recover at different rates.
Question to ask: Why do new colors appear after the picture is gone?
Lesson flow
Predict → demonstrate → observe → briefly explain → ask: Why do new colors appear after the picture is gone?