 This is a mathematical snack from the Association of Teachers of Mathematics. This is a mathematical world which is represented by a yellow piece of paper with some lines drawn on it. Here's an example. So I've drawn four lines and all together I have six spaces. There's also a red crossing point where two lines have crossed each other over. So this picture represents four lines, six spaces and one crossing point. Here's another example. And this time I've still got four lines and I've still got a yellow piece of paper. I have only five spaces and there aren't any crossing points. And here's another example. This time I've got a yellow piece of paper, I've got four lines and I've now got three crossing points and eight spaces. Your task is to explore how many different numbers of spaces I can make and different numbers of crossing points if I only use four lines on the piece of yellow card. Once you've had a go at that see what happens if you have more lines or less lines.