This is a brilliant resource which generates endless questions on calculating the area of a circle from the radius and diameter. There is also a third tab which asks students to work out the radius given the area. What is lovely is that each stage of the working can be displayed by clicking the square to reveal it. This would make a really good plenary to use with mini whiteboards and tell the students to show all their working, if anyone gets it wrong then you just click 'new question' for a brand new one! Thank you for sharing.