Sunday evening.
The owner opens the week on her phone.
Monday's 7am reformer flow shows eight of eight booked and a waiting list of three; the mat room at 9.30 has seven of twelve.
A message arrives from a teacher who cannot take Tuesday's lunchtime class.
The owner marks it for cover; the two teachers on the reformer cover list are offered it and one accepts within the hour.
The system messages the nine booked students with the substitute's name, and the class stays open for the last place.