When you offer a teacher a role, it will appear on the teacher's smartphone as a message. You can only make one formal offer at a time for a role
If they are interested, they have a certain amount of time to accept the role:
If role starts within the next 24h, time to accept a formal offer is 90 seconds
If role starts between 24-48h, time to accept a formal offer is 1h
If role starts more than 48h away, time to accept is 6h
If a teacher does not accept within the allocated time, you are free to offer the role to someone else, and the "lapsed" teacher has to reconfirm their interest for you to be able to re-offer them the same role.