 This is a mathematical snack from the Association of Teachers of Mathematics. Here is an egg box. This egg box can have 24 eggs fitted into it. This task is about fitting eggs into the egg box in a particular way, and that way is that every row and every column has to have an even number of eggs. I'm going to use six eggs as an example to show you how this works. I'm going to place my eggs on the tray. Two, three, four, five, and six. I'm now going to check to make sure that my solution works. I've got two in that column, two in that column, and two in that column. But I've only got one in that row and three in that row, but I have got two in that row. If I move that one egg to the top row, it now works because I have an even number of eggs in each row and an even number in each column. My challenge to you is now to work out is it possible to fit 18 eggs into that storage box with even numbers in each row and each column. And if it works, try other numbers. Which numbers work and which numbers don't? Can you explain why? Here's a way that I could do it where I drew the grid out, six by four, to represent the egg box, and I used milk bottle tops to represent the eggs. So all I can do is just place the milk bottle tops on the grid and move them round as I need to. If you haven't got milk bottle tops, you might want to use little bits of paper or cancers.