Prism Splits White Light
Three related teacher demonstrations: Prism Splits White Light, Polarized Plastic Stress Colors, Sugar-Water Rainbow in a Straw.
Teaching & key ideas
1. Prism Splits White Light
Materials: Prism; flashlight/sunbeam; white card
What you do: Pass narrow white light through prism.
What students see: A rainbow spectrum appears.
Question: Was the rainbow already inside white light?
2. Polarized Plastic Stress Colors
Materials: 2 polarizing sheets/sunglasses; clear plastic objects
What you do: View clear plastic between crossed polarizers.
What students see: Bright rainbow stress patterns appear.
Question: Why can clear plastic suddenly show colors?
3. Sugar-Water Rainbow in a Straw
Materials: Several colored sugar solutions; clear straw/dropper
What you do: Layer different sugar concentrations in straw/tube.
What students see: Colored layers stack.
Question: Which color has the most dissolved sugar?
Lesson flow
Predict → observe three demonstrations → compare what changed → choose independent activity station → cleanup/share.
Guiding questions:
Question: Was the rainbow already inside white light?
Question: Why can clear plastic suddenly show colors?
Question: Which color has the most dissolved sugar?