I'm slated to teach the photography merit badge to a group of boy scouts. The scoutmaster thought it would be a great experience for the boys to also get some hands-on experience using LF gear, and that's where my question arises. There are 16 boys, and they will be split into two groups. The first night, half the boys will shoot one sheet each of film, while the other group learns about digital cameras. I will later take those 8 sheets of film and develop them. The following week the boys will switch places.

My question is, I only have 4 film holders. I need a way to identify which boy shot which negative. I'm guessing we can't rely on the boys to remember which shot they took, since there will be a 2 week gap between when they shot the images and when they will actually see their negative. So, what can I do?