It's not voluntary. 100% of students are asked a question. In the eighties, this was entered into a classroom response system (a clicker where kids press a butt

It's not voluntary. 100% of students are asked a question. In the eighties, this was entered into a classroom response system (a clicker where kids press a button on multiple choice) and an eighties-era computer would process their responses for an eighties-era dashboard, presumably using one of those $20,000 CRT projectors. Today, it's cell phones and laptops, and they do a lot more than multiple choice. Students might be asked to highlight text in a passage (and the system shows a heatmap), to draw vectors, etc.