On Day 19 the challenge was to find all possible pentominoes – the shapes made from 5 squares. Spoilers below – go and try the task first if you want to have a go for yourself.
Here are the twelve possible pentominoes, made out of lego. Some of them have been fitted together to make an enlargement of one of the pentominoes.

Can you make your own set of pentominoes?
Can you make enlargements of any of the other shapes?
Can you make a rectangle that uses all the pentominoes?