Teaching and research experiences are regarded as an integral aspect of the graduate training program. All doctoral students are required to serve as teaching fellows for two terms at the TF level 10 or 20, typically during years two and three. During the first term of teaching, students must attend a training session conducted by the Poorvu Center for Teaching and Learning. First-year students are encouraged to focus their efforts on course work and are not permitted to serve as teaching fellows. A Ph.D. student who has fulfilled the teaching requirement is not permitted to serve as a teaching fellow without special permission from both the student's advisor and the DGS. In the rare instances this exception is approved, the student will only be allowed to serve at the TF-10 level.