Embryology quiz

I’m writing the quiz for my introduction to embryology lecture that I’ll be giving to the first years next week. The quizzes use the Turning Technologies interactive ‘clickers’ systems, and we use them anonymously. There’s no record of how well an individual scores within the lecture quiz – it’s just for fun (and instant lecturer feedback and concept checking, of course).
Last year we had a competition for boys vs girls over the whole series that went very well (albeit with a little cheating). This time around the embryology lectures will be spread wide across years 1 and 2, and there will be fewer of them. I don’t think I can use the competition format again. I’m sure if I asked the students not to cheat they would listen and refrain, but I think that the competitive element will be lost by spreading the lectures out over so much time.
Maybe I could pick the highest scorers for each lecture (but that misses the anonymous answering aim), or have teams per lecture without tracking through the year (but the competition got stronger as the year progressed and the scores built for each team). I’m a bit stuck. I’ll have a think about it.