Circles are one of the most common shapes. If you think about it, circles are just about everywhere - wheels, gears, pulleys - without circles transport and machinery would be almost impossible. So, with circles being so important, it won't surprise you to learn that they are one of the things you need to know about in KS3 Maths.
There are some special terms relating to circles which you will hopefully be familiar with - radius, diameter, circumference, arc, sector and of course π. In any circle the ratio of the distance around the curved perimeter to the distance across the circle through the centre is represented by π (the Greek letter pi) which has a value of just over 3 (3.1415926535.....)
It's a very good idea to get to know circles, their parts and the formulae associated with them. To help you, try this quiz all about circles. Take your time and read each question carefully before submitting your answers. That way, you won't end up going round and round and round! Good luck!