Wow! This looks very impressive (And great quick modelling, by the way! Bravo!)

What were your render times for this image? (And what are your system specs? so I'd know how to approximate that for my own.)

My main problem is really in the render times. I want a classsroom full of furniture, props and human figures, fully clothed. Even if I use proxy figures for the ones near the blackboard, it's still a LOT of stuff for the light to bounce off and slow down calculations.