Begin with the 'claim' on the bottom of the sheet. Students then explore cutting up the square on the hypotenuse to make it fit inside the other two squares. The power point shows an animated version of this to run through afterwards. I also like to give students a sheet of questions on A3 to see if they can work out how to answer them using what they have been working on. Good extensions include: Is there any other way we could cut the squares? What about if we put other shapes on the sides? Are there any rules now?