*For our full coverage of AAAS 2016, check out our meeting page.WASHINGTON, D.C.—Teachers who wonder if their class is engaged could one day find out by checking how synchronized their brain waves are with each other. That’s the conclusion of a new study that logged the neural activity of 12 high school students and their teacher with electroencephalography (EEG) headsets over 11 classes. This is the first time the technology has been used simultaneously on such a large group outside of the quiet and controlled laboratory setting, says neuroscientist Ido Davidesco of New York University, who presented the study at a poster session yesterday at the annual meeting of AAAS (which publishes Science). Not surprisingly, patterns of brain activity were more similar when students were all focused on the same task. But the researchers also found that when a student reported being more engaged, the frequency of their brain waves better matched the group. Activities the students liked more—group discussions and videos versus a lecture or being read to aloud—seemed to put them more in sync.