Christian Sherrill was trying to corral the attention of 150 students wrapping up a classroom activity and chatting with each other about their results. A handful were getting water refills, others were checking their phones.
“If you can hear my voice, clap once,” Sherrill’s voice boomed. A few people clapped, the room quieted slightly. “If you can hear my voice, clap twice.” More eyes turned toward the presentation screen. Most — not all — of the conversations subsided.
