This is the fourth video in the Algebraic Expressions series for the Year 9 Mathematics course. Looking how we can now reverse the process of the previous videos, I show how we can now start to factorise algebraic expressions. Looking at how to take the highest common factor, and then dividing the terms, we can quickly see how factorisation works. There are lots and lots of examples which support my clear and easy to understanding explanations. There is even some humour! What more could you want.