This picture is taken from a CD-ROM of photographs with activities for mathematics teaching. Published as Mathematical World in America and as Problem Pictures in the UK, Europe and Australasia.

Three-colored tile pattern

This pattern uses square tiles of three different colors. They are arranged so that two tiles of the same color never touch along an edge. The pattern uses equal numbers of the three colors.

Design a different pattern that also uses equal numbers of square tiles in three colors. The same color must never touch along an edge.

A snail crawls across the tiles visiting the colors in order: red, yellow, black, red, yellow, black...

Is it possible for the snail to visit every tile?

The photograph was taken in a church porch, Devon, England.

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