I do loads.
As above really-state when you put your price in that 'accessible' windows are cleaned.
Specify that any with pictures etc on will be missed.
Blu tak is a pain in the arse but we just take it off.
Needs to be as good as a domestic really.
Once teachers set work for the lesson-they get half an hour it so daydreaming, looking out if the window invariably.
When they get into the staff room they'll all have a chat about the quality.
I know this cause I used to teach.
Great little earners though. Do a top job and get friendly with the caretaker.
They'll point you to the staff room where there'll be coffee a plenty
