The object here is to make a perfect cube from the 25 "Y" shaped pieces that will fit under the very pretty cover. This puzzle was invented by David Klarner and published in the Journal of Recreational Mathematics in 1970. Originally it was thought to be solvable 236 ways. Later computer analysis showed that over 1200 ways were possible.
In addition to the cube, you can try to make different sized rectangles from rectangles from 10, 12, 16 and 20 fo the pieces. We provide a sheet with hundreds of shapes to make, which are more achievable than the cube.