Medieval stonemasons used a method to construct octagons using ruler and compasses... Is the octagon regular? Proof please.

If you know the sizes of the angles marked with coloured dots in this diagram which angles can you find by calculation?

The diagram shows a 5 by 5 geoboard with 25 pins set out in a square array. Squares are made by stretching rubber bands round specific pins. What is the total number of squares that can be made on a. . . .

Discover a handy way to describe reorderings and solve our anagram in the process.

This rectangle is cut into five pieces which fit exactly into a triangular outline and also into a square outline where the triangle, the rectangle and the square have equal areas.

The opposite vertices of a square have coordinates (a,b) and (c,d). What are the coordinates of the other vertices?

Learn how to use the Shuffles interactivity by running through these tutorial demonstrations.

Show how this pentagonal tile can be used to tile the plane and describe the transformations which map this pentagon to its images in the tiling.

We have four rods of equal lengths hinged at their endpoints to form a rhombus ABCD. Keeping AB fixed we allow CD to take all possible positions in the plane. What is the locus (or path) of the point. . . .

On the 3D grid a strange (and deadly) animal is lurking. Using the tracking system can you locate this creature as quickly as possible?

What can you say about the values of n that make $7^n + 3^n$ a multiple of 10? Are there other pairs of integers between 1 and 10 which have similar properties?

Could games evolve by natural selection? Take part in this web experiment to find out!