Today AP Physics 2 started the Electrostatics unit. The first topic was electron theory, which is review of last year’s class for all students (regardless of which class they took last year). Rather than a review lecture which would have little engagement, I finally had the idea to leverage peer instruction in this context. I presented a few notes on electron theory, emphasized the theme of explaining macroscopic phenomena from an atomic perspective, and then we spent the rest of class discussing conceptual questions via peer instruction. Students were much more engaged and I had much greater confidence in what they did and didn’t retain from last year.