This section is from the book "Modern Buildings, Their Planning, Construction And Equipment Vol3", by G. A. T. Middleton. Also available from Amazon: Modern Buildings.
When a Schoolroom is the principal room in a school with neither hall nor corridor, it should never be designed for more than 100. A room of even smaller size is desirable. Width should vary according to kind and arrangement of desks.
No schoolroom lighted from one side only can be approved. Gable ends should be fully utilised for windows, but there should be no superfluous windows opposite the teacher.
A school consisting of a single room should not contain more than 600 square feet of floor space.