In preparation for the discussion of continuous groups and their applications in physics, we began the class with a short and a bit of a handwaving introduction of the more abstract notion of symmetry, namely that of a symmetry of a physical law. We then moved on to complex numbers, which most students have seen before. After a brief introduction, students practiced working with:

**Complex numbers**in the rectangular form- Operations with complex numbers
- Complex
**conjugation**and**modulus** - Complex numbers as points in a
**complex plane**

Finally, students showed that complex numbers form a group under addition, (C,+).