A domino is made from two squares joined corner-to-corner and edge-to-edge, like this:

You may have come across dominoes decorated with spots, which are used to play games.

What if we joined more than two squares together?

There are two sorts of triomino made from three squares:

*You can explore the L-shaped triomino here*

By joining one extra square to the different triominoes, we get the tetrominoes - if you've ever played the computer game Tetris you might recognise some of the shapes!

If you join an extra square to a tetromino you get a pentomino - five joined squares.

**Can you find all the different pentominoes?
How can you be sure you've found them all?**

Once you've found all the pentominoes, you could take a look at Pentomino Puzzles to see some different shapes you can make with them.

## Comments

### R means directly right to the

R means directly right to the last box placed while U means directly up from the last box placed. There are three sets of pentominoes. First create a shaded box, the starting point, then add other boxes to make the pentominoes. The added boxes should be up or right to avoid making the same pentomino. The first set is the staircase set. We start with a UUUU, then URUU, the RURU, and then the RRUU. The second set is the long chain set. We start with a RRRU, then move the U to the left, making a joint. This makes a RR(U)R. The U in the bracket means the U is joined to the second R. Then moving the U to the left again, and then moving the last R to fill the U's place, we get R(U)R(U). Continuing from this "square with a part sticking out", we can move the last R and move it to directly on top of the shaded box, making URRD. We can move the D (down) to two other places in the shape URR, making these shapes: UR(U)R and URRU. The other set is a cross and a T. The area of the pentomino puzzle is 60, meaning that there are 60/5 pentominoes in total.

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