Pedro wrote this for his Dutch readership, but it’s worth spreading to English speakers. He wrote:
For Corona, one of my most read and shared posts was about what we call time on task. Earlier I also wrote about the danger of interruptions for learning. New research by Kraft & Monti-Nussbaum (2020) shows this and shows that there are far more interruptions in the classroom than you would think. Now that time at school has been so preciously identified, this study deserves extra attention.

Children who arrive late -> interruption. Someone from the secretariat who comes by -> interruption, … But more importantly, the interruption of learning lasts much longer than the time of the actual announcement, for example. The effort that the teacher and students have to invest to return to working is also: