This lesson went well with my honors students this week, and I'll see how it goes with my lower track students next week. The idea is that the only legitimate context for much of the material in Algebra II is its scientific context, and I used this to give my students this context while practicing solving rational equations.
In my mind this is a step up from the "average rate" questions that dominate most of the applications of rational equations that I've seen. This is also easier for students (and this teacher) to understand and explain than resistor and circuit problems.
Here's my power point presentation, which I used to tease them ("Ever wonder why objects in your sideview mirror are closer than they appear?"), leading into the worksheet.
They split up into pairs and worked on the worksheet together.
Thin Lens Worksheet