Thompson & Thompson Genetics in Medicine is a fantastic resource for studying medical genetics, but even though I think it is very readable it may be more information than what you are looking for at this point. If you would like a well-written book that goes into slightly less depth than T&T look into Medical Genetics by Jorde, Carey, and Bamshad. Your school library should have both and there are practice questions at the end of every chapter. Good luck studying!