This course is taken in the first two weeks of the first year of the Oxford Mathematics degree. It introduces the concepts and ways of mathematical thinking that students need in the years ahead. Much of the context will be familiar from high school but the way we think and write about it, and construct arguments and proofs, will be more rigorous. In summary it is a recap and a pointer to what is to come for our students. We are showing the whole course over eight lectures. This is Lecture 3 and continues the previous lecture's look at sets, and specifically algebra of sets, truth tables and cardinality. You can watch many other student lectures via our main Student Lectures playlist (also check out specific student lectures playlists):    • Oxford Mathematics Student Lectures -...   All first and second year lectures are followed by tutorials where students meet their tutor to go through the lecture and associated problem sheet and to talk and think more about the maths. Third and fourth year lectures are followed by classes.