personal contact in a large lecture class

It is a challenge to have more contact with students when there are approximately 500 young people taking the class.

One small thing that I do is after the 2nd exam. Exams are stressful moments in a course. Before the exams I organize review sessions etc., but after the exam I look at how each student did in the 2nd exam compared to the first exam. I contact each student (via email) who noticeably did much better in the 2nd exam compared to the first and congratulate them. I also contact students who scored noticeably worse on the 2nd exam and offer to meet to plan how they/we can help.

Students reply to me after these emails, generally appreciative, and I have now approximately a dozen one-on-one meetings scheduled.

The core idea is that if I was teaching a class of 20 students, I would be able to walk up and congratulate the students who improved, or quietly talk to those who did not do so well. In a class size of 500, it is harder to achieve this level of personal contact, but it is still possible, and it is still important or perhaps more so.