How to use these videos
Set out some paper, your calculator and your pencil case. Fire up your textbook, find the page, watch the video - making notes and trying to answer the questions posed in the video - and then do some questions from the textbook!
Remember active revision is a lot more effective than passive listening.
Proof
Book 2: pp280 - 289
Counterexamples (Box Video)
Direct Proof (Box Video)
Even and Odd Number Proofs (Box Video)
Quadratics
Sketching Quadratics (Box Video)