Question
How much of the Oral Law was taught to Moses?
Answer
The Talmud says that "Even what a diligent student was destined to teach before his master was already said to Moses at Sinai" (Yerushalmi Peah 2:6), but this may not be intended literally, i.e. it may mean only that all these things were implicit in what was said to Moses at Sinai. The Talmud (Menachos 29b) tells us that G-d allowed Moses to attend a lecture by Rabbi Akiva, but Moses didn't understand the discussion; this implies that the details of the material in the Talmud and Midrash weren't (yet) known to Moses. The basic Oral Law was certainly communicated to Moses, but the Oral Law has continued to expand ever since in response to the needs of every generation.