Look at the air conditioners in the windows of the original 1926 main entrance to Willard School. We didn't have them in our house until I was in high school but we sure could have used them. There were many days when our own sweat from the heat had us glued to our seats. All the teachers could reasonably do was lower the shades if the sun was shining through the windows and maybe turn out the lights. Neither actually did much to lower the ambient temperature of the room though it did give the appearance of taking action to beat the heat. At some point before they added air conditioners to all the classrooms they did put one in the principal's office. Mr. Daly, Princeton Alum, was a tireless, year round worker and no doubt rated the modern convenience. Not to mention it was a productivity enhancer.
The same could not be said for the students in classrooms, especially in the "new wing" completed in 1966. It was built with windows that allowed for no escape and thus blocked the wind and any chance to feel a cooling breeze. Take a look at the windows on the left of this picture below. They opened wide enough that we could have jumped out. Plus they had shade trees on this side of the school that provided some relief against the heat. The "new wing" had fewer trees and thus the sun beat down on the classrooms without concern for people trying to learn something. Even on the hottest days it felt cooler outside than inside our classrooms. Air conditioners are a great idea for the promotion of learning and for producing working conditions which encouraged teacher retention.