Make a cube out of straws and have a go at this practical
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!
Look at this image for a short while before turning away.
Here is a pdf document containing the image.
This image is taken from the NRICH Mathematics Posters CD called "Exploring Squares" published by Virtual Image. More details of this and the "Exploring Circles" CD can be foundhere.