 This is a mathematical snack from the Association of Teachers of Mathematics and it's all about fitting squares together. There are only two rules for fitting them and these are that you can place squares full edge to full edge or you could place the squares by half an edge to half an edge. So with four squares I could make a shape like that. Now the next thing we're going to do is to work out the perimeter or currently perimeter as we go around the edge of the shape. So here we go. I just need to remember where I'm going to start. I'm going to start at this at this bottom left hand corner. So I'm going to count one, two, two and a half, three and a half, four and a half, five and a half, six and a half, seven and a half, eight, nine, ten, eleven. So the perimeter is eleven units long. Your challenge is to try to find all the different possible perimeters using the four squares and placing them using the rules from before.