What is the difference between Supplemental Instruction and Tutoring?

SI sessions are held at the same time every week. Students can drop in during scheduled SI sessions and are not required to sign up in advance. SI sessions are typically larger than tutoring sessions. SI Leaders attend regular lectures for the course and prepare agendas and activities for their sessions. SI Leader will also hold exam reviews. 

Tutoring is by-appointment only, and students must sign up in advance (no drop-ins). Tutoring sessions are small-group sessions (smaller than SI). Tutors have experience taking the course before, but they do not currently attend the lectures.