Large Class Teaching
There's no doubt that teaching a large class is a challenge. The teaching skills one uses in a small class don't necessarily carry over to be effective in a large class. Teaching a large class (over 50 students) is much more of a large-scale performance than it is having the feeling of an intimate classsroom setting. Your voice and your visuals need to be "larger than life". Microphones are usually used for amplication and PowerPoint is typically used to project large-scale notes and visuals.
Large lectures tend to be much more uni-directional rather than interactive. Instructors prepare lessons and deliver them using almost theatrical techniques - larger gestures and facial expressions and movement from one side of the room to the other. Students typically take notes, memorize those notes, and regurjitate them for the exams.
There are ways, however, to engage your students in large lectures so they get more involved with the material. Professor Eric Mazur, a physics professor at Harvard, uses a technique called Collaborative Learning where he stops his lecture every 10 minutes or so and asks his students a multiple choice question. After they answer, they have 1 minute to discuss their answer with a neighbor. He then brings the class back together and explains what the correct answer is. Mazur has had tremendous success with this technique and has found it gets students thinking rather than just being passive note-takers.
Wilbert McKeachie (2006) also believes that active learning can be used successfully in large classes. He recommends such things as assigning students to study groups outside of class, having students email the professor questions that they may have, and having students use clickers in class to respond to questions the instructor may pose. He strongly recommends that instructors use websites when teaching large classes to communicate with their students about the course syllabus and handouts, announcements about the course, reminders about due dates, and posting of grades.