In Physics 11b, students engage in peer instruction by discussing the answers to questions posed in class. Before the activity, students need to have completed the reading and reviewed the concept questions. In class, students are given questions that they answer using an online system similar to clickers. Afterwards, students discuss the question with their neighbors and then enter their responses again. The answer to the question is given and discussed if a large portion of the class still has trouble with the question. This teaching style is used throughout the semester. The instructors find it very helpful for addressing conceptual roadblocks in the material. The questions need to be reasonably quick to answer and emphasize core concepts of the class. Questions involving memorizing specific information tend not to be useful.