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.
These should be separate for each department and sex. In large schools more than one to each department is desirable. Entrance doors should open outwards as well as inwards. A porch should be external to a schoolroom, and a door having outside steps requires a landing between the door and threshold.