In a huge cavern in Transylvania, a hundred thousand bats gathered for an emergency meeting, clinging in tribal clusters from stalactites. At the center of the cave, various national representatives nudged and wedged themselves into better spots, until a huge ancient bat with scarred wings, raised his head and emitted a sonorous whistle. All fell quiet.

First, put your cell phone policy on the syllabus: “No cell phone use in class.” Before printing, debate whether or not to add “please.” These are adults. Would you want to be commanded? Add “please.” But they should know you mean business. Delete “please.” Put it in. Take it out.