Benham Disk Color Illusion
Faint colors may appear even though the disk has no colored ink.
Teaching & key ideas
What you do: Spin the black-and-white pattern.
What students see: Faint colors may appear even though the disk has no colored ink.
Why it works: Different visual receptors respond at slightly different rates.
Question to ask: Are the colors really printed there?
Lesson flow
Predict → demonstrate → observe → briefly explain → ask: Are the colors really printed there?