hi Daisy....i'm going to assume that the walls are glass....maybe it is possible to have a someone take a panal of glass out and put in a door or window??
or a glass cutter to make a small hole you can cover with some kind of material??or try a couple fans to circulate the air...
good luck...
diggy

Without ventilation, impossible to grow anything.

With passive ventilation, but nothing else, you can try hot weather crops like okra, eggplants, perhaps peppers.

Better still, install an exhaust fan on the east side opposite a vent or door cut out (on the west side) as suggested above.
A misting system coupled with at least passive ventilation will also be effective.

Do you have a woodworking shop in your school too? If you do would it be possible to take out a couple of glass panes--on opposite sides and replace them with windows. I don't know how your greenhouse is built but it may be possible if it has a wooden frame.

You could also remove the panels and use the sticky backed velcro and greenhouse film to replace them. I don't know how practical it would be in a school situation though. You really need cross ventilation. Plants need air circulation. I don't think there is any permanent solution other than refitting the greenhouse with vents

As for now--Are there windows in that classroom opposite the greenhouse. Opening the windows and the greenhouse door and a fan blowing the cooler air from the windows into the greenhouse. Not ideal but it may help

Thanks so much for the responses.

There are actually two small windows at waist height at either end of the greenhouse. Also an exhaust fan. However, the exhaust fan has to be turned off during school hours because it makes so much noise the teachers can't function. Even with the fan on and windows open it still gets to be 110 F easily.

Unfortunately, the structure is glass and steel so I don't think it would be easy to retrofit windows/vents, but I'll ask someone more knowlegable.

I think I will try the shade cloth first and see how that works. I can get it free from a supplier that supports our program - just not sure how i'll attach it.

Usually it's not such a big problem since i get the plants out for the May long weekend anyways and it's not that warm before then, but this year we've already had many days over 25 C and it's roasting in there.

Someone else suggested I also try a box fan blowing at the other end of the greenhouse too (when class isn't on of course).

You should also add a misting system to cool down the temps.

If your frame is steel not aluminum you could attach the cloth with magnets. A small fan set in front on a window will blow across to the other window. You can take a tip from old time southern ladies, if you have access to a block of ice you can put it in front of the fan. OR you can freeze jugs of ice if you have access to a freezer. It would take changing and freezing a few times a day but would be less messy than the block.

Oilpainter, those are brilliant ideas. Thank you

Whitewash!