Parallelogram
A parallelogram is a rectangle that has been leaned on, and its opposite sides have never met.
Zigzag
A zigzag is a straight line that kept changing its mind, and is now the shortest route to nowhere in particular.
Trapezium
A trapezium has one pair of parallel sides in Britain and none in America. The shape has not been told.
Semicircle
Cutting a circle in half produces two semicircles, making the semicircle the more successful shape.
Crescent
A crescent is a circle that has had a bite taken out of it and is too polite to mention it.
Rhombus
A rhombus is a square that has been leaned on, and is not a diamond because it isn’t worth anything.
Cylinder
A cylinder is a circle that refused to stop, and kept going in the same direction until told.
Spiral
A spiral is a circle that could not decide where to stop, and has been going round about it ever since.
Dice
On a standard die, the numbers on opposite faces always add up to seven.
Pentagon
Every child who has ever drawn a house has drawn a pentagon and been told it was a house.