I am trying to microphone a classroom with approx. 40 to 50 students. They are sitting on chairs with tables in fron of them. The room size is approx 30 ft wide and 40 ft deep. I was thinking of using nine hanging microphones. I am trying to pickup questions that the teacher will answer. The teacher is wireless miked. The students questions will not be broadcast through the speakers, just for recording purposes. Any thoughts?