Rachael,
I believe that the C500 Experiment Kit is intended for a single student's use, however if your students work together, then it should be fine to use the same kit. If you had 3 students using the same kit, I think I would consider opting for more than one kit. There could be enough leftover material that you could do the experiment more than once, but I don't think it was planned to be that way.
Blessings,
Carrie