Sets and Venn diagrams

Union, intersection, difference and complements, with a Venn diagram and a counting check. About 8 minutes, KS4 / University.

What you will do

1. A collection of things. A set is a collection of distinct things. The order does not matter and repeats count once.
2. Union and intersection. A B is everything in A or B. A B is what is in both.
3. Difference and complement. A B is in A but not B. With a universal set U, the complement A' is everything in U that is not in A.
4. Counting with sets. |A B| = |A| + |B| - |A B|: add the sizes and take off the overlap counted twice.