Optical illusions

This section is mainly ‘just for fun’, since solutions are easily found by measuring, even though these normally contradict students’ initial impressions. The puzzles could be used to introduce lessons on topics such as parallel lines or 3D shapes, to stimulate discussion or in after-school maths clubs.

Several of the optical illusions lose their effect when used with a projector so are provided as PDF worksheets only (not as PowerPoint presentations).