I have been putting off doing maths revision for at least a week now but I finally revised today. I started the chain rule and when I read the first page I wept at how complicated it was. (Figure of speech. I didn't really cry). But then I went to youtube and they had a tutorial on it and it was actually really easy. You just need to ignore the way they do it in the text book and then learn this way and its easy. God bless you MathsTv!