pentomino is the name of a shape formed by joining
five squares together edge to edge.
There are twelve pentominoes altogether - can you find them all?
There are other possibilties of course (the number of squares is in brackets):
1 domino (2),
2 tronimoes (3),
5 tetronimoes (4),
35 hexominoes (6),
108 heptominoes (7)...
No one has found a formula yet!