We took a few notes today. I just told them about the difference between concave and convex mirrors and what that means about the sign convention we use in the lens equation. It's kinda boring, and not very hands-on of me, but this move saves me some time. Which I used to get us started to talk about the next concept. We listed the three ways light can behave when it hits a boundary: it can be absorbed, it can be reflected, and it can be transmitted. We know the ray changes direction when it is reflected; let's see if the path of the ray changes when it is transmitted!
When I showed the class the three pins method with the semicircular Petri dish, drawing in the normal and showing the angles really helped because even though the students didn't realize internalize it, it caused students to realize their angles seemed off and then think about how we measure angles. I really liked this new move.