Students at the Oswestry Centre were introduced this week to the special relationship between a circle's diameter and circumference. After carefully drawing their own circles, they measured the diameter using a ruler and then carefully wrapped ribbon around the circumference to measure. We then compared our practical measurements with the formula calculation C=𝜋d and were amazed to see how closely our results matched. As a class we experimented with lots of different sized circles and students were surprised to see such similar results.