 This is a mathematical snack from the Association of Teachers of Mathematics for you to enjoy. This video shows how to play a simple game called one or two. We start with a set of counters, maybe somewhere between 12 and 20, and we're going to take it in turns to take away either one or two of the counters. The winner is the person who takes away the last counter. Christine, would you like to make a start? I'm going to take two counters. I'm going to take two counters. I'm going to take two more counters. I'm going to take one counter. I'm going to take two more counters. I'm going to take two counters. I'm going to take one counter. I'm going to take one counter. I'm going to take two counters. And I'm taking the last counter so I win. Kristin, shall we play another game? Here we go. By the way, do you want to start or? You start this time. Do you think it makes a difference? That's something we could find out, isn't it? Right, I'm making the start. Here we go. I'm taking away those two. I'm going to take one. I'm going to take two. I'm going to take two. I'm going to take one. I'm going to take two. I'm going to take one. I'm going to take one. I'm going to take two. And you've won because you've taken the last counter. So do you see how to play the game? It's very easy. Can you work out how to win? Does it matter who starts? Change the rules if you want so that the person who takes the last counter loses. If you haven't got counters, you can always make marks on paper and cross them out in each turn. So with this activity, this is your task. Have fun.