The teachers of the group have a series of questions that the students have to answer. Some students get to be a teacher, they get to roam around their group asking questions like "Why did you do it that way? How would you solve it? Can you explain your answer to me?
The teachers model it for the students first so they know what they are doing. Then they hand out the sheets and the lesson begins with the first question.
You cant pick the same workshop every time because you need to learn different strategies and techniques. If you already know the strategy its probably a good idea to refresh your mind. You also have your friends around you to help when you get stuck, but the teacher is probably the best idea.