My ds is in year 11 and I'm trying to get ahead of myself by ordering his revision guides now, but there's so many different ones relating to different examination boards.. Are they all completely different ? Do I need to speak to the school to find which board they're using? And will that board be the same for every subject or could they be using a variety of boards across different subjects? I don't want to buy him revision guides that have no relation to the exam he'll be doing in the end... Any advice gratefully received..