Make a cube out of straws and have a go at this practical challenge.
Reasoning about the number of matches needed to build squares that share their sides.
How can the same pieces of the tangram make this bowl before and after it was chipped? Use the interactivity to try and work out what is going on!
Count what you see: how many bricks? sectors? circles?
Identify how you think the pattern would continue: how many will be in the next layer/ level?
Look at what would happen if you started (or ended) with a different number of items: how many will there be in total?