I just published a new unit of instruction on

Sets and Set Theory. When designing this unit, the first thing that dawned on me was the notation. Students often become overwhelmed by set notation, making it difficult to learn the concepts. So my goal was to start off with an elementary and visual approach, with real-world connections. I did not introduce

Set-Builder Notation until later in the unit.

The other difficult task was deciding when to introduce

Venn diagrams. This was done in stages, so that other topics, such as basic notation, types of sets, and equality could be introduced first. It was a lot of work over the course of many months to finish this unit. I am quite proud of the final result.