Kraft and Monti-Nussbaum studied outside interruptions in Providence Public Schools: intercom announcements, phone calls, staff visits, and students arriving late. They combined district-wide surveys with timed observations of 63 high school class periods. They found that a typical classroom is interrupted more than 2,000 times a year. About half of those interruptions trigger further off-task behavior, and together they cost roughly 10 to 20 days of instruction annually. Tardy students were the most common cause, and phone calls were the most costly per instance. Principals consistently underestimated both how often interruptions happen and how much they hurt learning. Because most interruptions come from school staff and vary widely between schools, the authors argue they are highly preventable. Their remedies include cutting unscheduled announcements, moving routine messages to email, and addressing tardiness. journals.sagepub.com/doi/ful…