Supplemental Instruction (SI) is an international, peer assisted study program designed to improve student performance by combining "what to learn" with "how to learn."  SI targets selected math and science courses, and provides 2-4 regularly scheduled sessions each week. Attendance is voluntary and free to everyone in the class. The informal sessions, are facilitated by leaders who have demonstrated proficiency in the course content and who have received training in using a variety of strategies and techniques to empower students.  Studies show that students who regularly attend SI earn better grades, and withdraw less often than non-participants.