Keep the register, change the tool
Teachers already know how to call a register. Keep the routine — same time, same order, same person responsible — and change only where the marks are written.
Start with one class and one week
Ask one willing form teacher to mark on the screen for a week. Fix what slows them down before adding classes; a tool that saves the office time but costs the teacher five minutes will be quietly abandoned.
Make the offline question explicit
Many classrooms have unreliable connections. Decide what happens when the network drops: marks held on the device and synced later, or a paper fallback entered the same day. Unexamined, the answer becomes “the register is missing”.
Mark present by default, not absent
The fastest register starts with everyone present and records only exceptions. The same principle applies to lateness: one tap, one reason, no typing.
Use the data the same week
Attendance is only worth capturing if someone acts on it. Agree who reviews absence patterns weekly and what triggers a call home, then make that list part of the routine.