I like the overall concept, but we had fun picking apart your last one so I'll start...
1. Miss Alveres looks nice (though less sexy) in this one
2. desk clutter much improved over previous picture
3. biology, chemistry, algebra and geometry all on one board?
4. lighting looks like you just took the roof off
5. two students not paying attention?.. we know this never happens in school 🙂
1. Yes!
2. I don't think a calculator would be useful in a chemistry class 🙂
3. I think it's bio + chemistry. The atom's structure is also studied in chemistry. 🙂
4. Interiors are hard to illuminate, but if I remember correctly, you could use something like HDR lamps?