Currently, i'm doing the CREST award for physics, and my topic is about different methods of finding out the refractive index of a medium. I have already tested out few ways, and now i am thinking about a method where a formula n=c/v will be used(n-refractive index, c-speed of light in vacuum, v-speed of light in medium). So, what i am looking for is the way to carry out an experiment where i will find the speed of light in medium. I have thought about using light-sensitive screens, but i suppose that difference will be so insignificant that results will be far away from being accurate. If anyone has any ideas i would be happy to hear them.