Two examples of teaching aids available in the Teaching Materials Center are demonstrated by Au graduate students. nadimi Bibi (rear), graduate English student, listens to a taped lecture while Egilda Zuest, graduate modern languages student makes use of a programmed didacter teaching machine. The didacter flashes questions on a center panel requiring either yes-no or multiple choice answers. When answered wrong, the machine provides for extra review or practice until the subject material is mastered.