For OCR, Rosenhans study on telling sane from insane, Milgrams original study on Obedience, Reicher and Haslam's BBC prison study, Freud's study on Little Hans. Just to name a few.
You're expected to know details of the sample, the procedure, the results and applications of the results. You're also expected to apply things you learnt in unit 1 to evaluate and suggest changes to the studies.