Hiroshi Ishiguro gave a lecture to a group of young students. We employed CommU, the desktop social robot, to manage the questions and answers for the talk. We encouraged the students to ask questions anytime. Half of the classroom was told to ask questions by raising their hand while the other half was shown an online messaging system developed for CommU, which allows the audience to post questions, which the robot would directly say. We had a gatekeeper to monitor for invalid sentences. In the middle of the presentation we asked the students to shift roles. The robot used a neural network based estimator of interruptibility to find the best time to speak. We did not expect too many questions, but the audience really embraced using the robot. They posted 44 questions to the presenter through CommU. On the other hand they asked 8 direct questions by raising their hands and standing up. Students thought that they gained more information from the lecturer using the robot than using the conventional method. In this instance we didn't stop the students from asking too many questions, but in a real-world application the gatekeeper will have to play an important role.