One of my friends - who just started teaching high school biology this year - has more than 500 students. She has three regular classes of 30 or so, whom she sees everyday, plus many classes that she sees once or twice a week for labs. In about 2-3 weeks she should reliably know the names of all the students in the three regular classes, but I wonder if she'll ever know the names of all the others. And how can you do a good job teaching someone when you don't even know them by name? Good grief!