"Contacting parents via text message, phone call or email took approximately three minutes per student. Gathering and maintaining contact numbers adds five minutes of time per child, on average. The time to generate a missing-work report can be almost instantaneous or take several minutes depending on the grade book used and the coordination across teachers. For this experiment it was roughly five minutes. Teacher overtime pay varies across districts and teacher characteristics, but a reasonable estimate prices their time at $40 per hour. If teachers were paid to coordinate and provide information, the total cost per child per 0.10 standard-deviation increase in GPA or math scores would be $156” (as compared to $538 for a recent intervention providing financial incentives for students). "