We did examples of modular arithmetic (Sections 4.12-4.13), including using repeated squaring to compute large modular powers with only small intermediate results.
We then looked at set-builder notation, vacuous truth (set relationships involving the empty set) and some gotchas with set notation.
We were patient with the squeakings of a lost electronic device, despite the considerable temptation to drop it into Margaret's board-washing pail.