In Brissie our school didn't have aircon - but then again most of the houses don't. If you're acclimatised to aircon all the time, then sending a kid to school without aircon is difficult for the kid.

Also depends on the design of the school, IYKWIM? My Brissie school (private) was built by convicts, and the architecture was wide verandahs so the sun didn't hit windows, and the breeze could flow through. But without that design it would have been unbearable - I find that buildings down here in Melbourne are hotter than in Brissie cause there's no verandahs, no eaves, no cross-breezes ...