Agree with Gaz, do keep a copy for yourself, sometimes you might find some case studies don't come back. My IHM case studies disappeared but I did have them saved on pc. With regard to case studies I am not sure what your college requires, some require a brief synopsis of the treatment, a history of the client, lifestyle etc and others require you to detail what stroke you started with and what you did next etc. Perhaps your tutor could guide you to what is required.
I agree with Hemelgirl, as soon as my case study left, I wrote up the notes whilst fresh in my mind, so much easier than trying to remember and being overwhelmed by them all. It is hard work but so worth it in the end.
I wish you success and best wishes during your course,
Love & blessings,
Rachel