A grade nine maths class was losing about a third of its students partway through the session, consistently, and the drop happened around the fifty minute mark.
We assumed attention, then timetable, then teaching. We asked the students, which we should have done in the first week, and the answer was data. They were on monthly mobile packages and a video class was consuming enough that they were rationing the second half of it in the last week of every month. The drop off was worst in the final week and that was visible in the figures once we knew to look.
Two changes fixed it. We built the audio and slides mode, which uses a small fraction of the data and works on a connection that would drop a video call. And we made every recording downloadable so a week could be fetched in one go on a good connection.
Attendance through the whole session went from about two thirds to over ninety per cent, and it no longer falls at the end of the month.
This is on our work page because it was the most useful thing we have ever learned and we learned it embarrassingly late. Ask the students.
