PURPOSE: Classic size illusion with a humorous twist.
DESCRIPTION: Set the two figures on an overhead projector with the red one below the blue one and ask the class which one is larger. (The red one, of course!) Suggest that the reason is that red wavelengths are longer than blue. Then remove the blue one from the projector and stretch it, replacing it below the red one. The blue one has become larger.
SUGGESTIONS: We have another red figure which actually is larger than the blue one.
REFERENCES: (PIRA unknown.)
SETUP TIME: None.
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