Faculty at hundreds of colleges and universities are using small electronic devices similar to television remote controls as part of their in-class instruction. Commonly referred to as "clickers," the devices allow students to respond to instructor questions by choosing one of several options or, in some cases, by entering a numeric answer.Answers are transmitted by either infrared or radio frequency signal to a receiver connected to a computer, which logs the responses and can track individual students' responses, as for a quiz, or display responses from the entire class anonymously. Faculty who use the devices said that because they allow students to respond anonymously, they encourage participation from students who might be too shy to answer verbally in class, and they elicit more honest answers on controversial subjects. Stephen Bradforth, a chemistry professor at the University of Southern California, said that after he began using clickers in his classes, attendance and participation increased. He also noted that the devices force professors to think differently about how they teach their courses.