A very belated thank you for whoever it was that mentioned Quizlet. It was probably months ago when DS was in his phase of "nothing can be done to make revision easier" because he shot it down immediately. He's altogether more open to suggestion at the moment and I put it forward again as an aid to history revision - he's good with the story and names but it's dates that elude him. He looked at it, made a set of cards and shared them with friends.
I am beginning to think that alien abduction is the only answer to the change in him over the last few weeks. I just hope that they don't bring my son back until the end of June as the podcreature seems to be doing a better job of revision than he was.