Editing Missing square puzzle (section)

{{Short description|Optical illusion}}
[[File:Missing Square Animation.gif|thumb|right|Animation of the missing square puzzle, showing the two arrangements of the pieces and the "missing" square]]
[[File:Missing_square_puzzle-AB.svg|thumb|right|Both "total triangles" are in a perfect 13×5 grid; and both the "component triangles", the blue in a 5×2 grid and the red in an 8×3 grid.]]
The '''missing square puzzle''' is an [[optical illusion]] used in [[mathematics]] classes to help students reason about geometrical figures; or rather to teach them not to reason using figures, but to use only textual descriptions and the axioms of geometry. It depicts two arrangements made of similar shapes in slightly different configurations. Each apparently forms a 13×5 right-angled [[triangle]], but one has a 1×1 hole in it.