Circles are awesome! That is certainly true but it is also the name of a fantastic website showing how circumscribed circles can be constructed. You can also move around the points and see the effects on the circumscribed circle in real time.
Why not work your way through the steps in the presentation getting your pupils to produce their own circumscribed circle as shown on the website? A lovely example of using ICT to support learning.
A huge thanks to Nilo de Roock for the recommendation of this great website. You can visit his blog here.