While we have students covered with many functions, not sure why teachers are not allowed to log their time daily? The students attendance can be deployed using the same concept and approach (each teacher has sign-in/sign-out time), while reporting can be only conducted by the admin (business owner). That could be the teachers' time sheets. With a little control not to allow the teacher to make any change once the data is entered.

Of course, every teacher can only be allowed to enter his/her own time sheet.

Hope that helps.
mk