As class size increases, the professor's ability to check for understanding and learning of individual students decreases proportionately. Imagine trying to collect feedback from 240 physics students simultaneously. It can be done. In this particular physics class, the professor starts each day by lecturing for about 10 minutes. Then he asks a set of questions that he describes as a concept test.
Students record their answers on palm top computers distributed throughout the lecture hall.
Once the computer records the individual answers, the professor directs the students to talk with the other three students on their team about the question. As these discussions occur, the professor participates by listening to their misconceptions as well as their correct answers. As he roams around the room, he learns how the class members are perceiving the material. After a few minutes, students are asked to record a second answer to the question. They're free to change the response they gave earlier.