Not familiar with the 9-1 books but I used the revision guides for science last year, I'm presuming they are similar. I wrote out the whole page- trying to look back at the page as little as possible and highlighted important things. When I'd done this for everything I needed, I read the pages out loud and if there's something I didn't understand, I learnt it off by heart- this helped SO much in many exams, just found myself writing exactly what I had learnt.