I did SHPEP at Columbia. We were enrolled only in 2 science courses, and it is dependent on your transcript. So they see which courses you've already taken, so they don't put you in them. Then they see the courses that you're taking the upcoming fall and place you in that. And you have that class monday-thursday in the mornings. So its basically like a summer class; there's quizzes and exams and you learn a lot of info at a fast pace. It's basically so that when you take the course in the fall at your home institution, you'll have exposure to the material and do better than your peers and boost your GPA. I did orgo and anatomy/physiology.
The columbia site offers those two classes, as well as biochem, stats, pysch, physics, and gen chem