A pentomino is a polyomino composed of five congruent squares, connected along their edges. There are 12 different free pentominoes, that can be named by letters:
We can 3dprint them, draw them on a paper and cut out, play it online, or buy them.
For 3d printing, this is the link.
The square is not needed for our purpose neither the box.
You can play to fit them all on a 5×12 rectangle (there are 1010 posible solutions) or the easiest 6×10 rectangle (2339 posible solutions)
There’s a nice free book for kids, where you can build shapes that looks like animals or other funny things. Take a look:
If you want to play on the computer the link is:
Printe and cut out pentominoes from this free pdf: