Join the midpoints of a quadrilateral to get a new quadrilateral. What is special about it?
Semi-regular tessellations combine two or more different regular polygons to fill the plane. Can you find all the semi-regular tessellations?
Can you find a way to identify times tables after they have been shifted up or down?
Join pentagons together edge to edge. Will they form a ring?
Take any triangle, and construct squares on each of its sides. What do you notice about the areas of the new triangles formed?
Follow the instructions to create a regular pentagon. Can you prove it is indeed regular?
These secondary problems have not yet been solved. Can you be the first?