Stay after class to briefly discuss the lecture and answer questions for students who are interested. Try not to lecture behind a desk or a table, this can separate you from your class. Engage the students in the same manner that you would if you were in a smaller setting. These practices can do a lot to show students that you are interested in them and you are accessible. The instructor asks a question or poses a problem.
Students spend a minute or two thinking about an answer or solution.
The instructor then may ask for several students to share their answers with the whole class. This method need only take a few minutes of class time.