We decided to reuse our used christmas cards to make a new decoration for next year. We used the compass from our maths set to draw out 20 circles with a radius of 4cm. We then used the radius to mark/divide the circumference of the circle in three (Pi = 3.14). We joined these three points to make an almost equilateral triangle. The rest of the instructions can be found here

http://quiltedturtle.blogspot.ie/2008/11…

This lesson had loads of maths and geometry skills. I think this would work at any time of the year using cereal boxes.