You could print off this sheet with the shapes drawn so you can try out your ideas. Or you could make the shapes on a pegboard.
You might like to cut out the shapes first. Then you could try cutting each shape and checking to see whether the two parts are the same - perhaps you'll need to turn one of them round!
Andrew decorated 20 biscuits to take to a party. He lined them up and put icing on every second biscuit and different decorations on other biscuits. How many biscuits weren't decorated?