The past two Mystery School photos taken from the 1939 Education Week booklet have been far too easy (particularly for Janet), but this one will not be, trust me! The view of the sleeping children, looking out of the open doors, has no clues like the past photos, so I think it is going to be hard to name the Mystery School.
I am off on holiday to Sicily for a week, so you all have time to ponder over the photo. There is a second photo, taken at the same time, looking at the same room, but from the outside. I will leave you guessing for a week, and when I am back I will email the second photo to Jennifer, she can add it to the page, and probably then it will be easier to establish the school!
As promised, the exterior shot for the mystery school. Does this help?