All undergraduate and graduate courses at Princeton are taught by members of the faculty. The typical undergraduate course is divided between lecture and discussion (or preceptors) sessions, the latter of which are sometimes conducted by graduate students with appointments as Assistants in Instruction (AIs). AIs are appointed by the chair of the department and are generally reserved for second and third year students who are in good standing in the graduate program. AIships carry small stipends over and above fellowship support and are excellent ways of preparing to teach as well as gaining additional competency in a particular subject area. Princeton University offers additional instruction in teaching skills for foreign students through a mentoring program prior to the fall semester, sponsors a university-wide learning laboratory to assist with learning how to teach, and offers several interdepartmental courses in teaching that include internships at community colleges.