It's bizarre.
Yes it's warm, yes it's uncomfortable and yes it's important to stay hydrated and use sun cream, but there really is no need for avoiding normal day to day activities.
As long as you're not a total dipstick who sits in a car all day with the windows closed or walks around wearing thick black winter clothes and boots, you won't spontaneously combust because it's hot.
What a bunch of precious over reactors.
Send your kid with a small light rucksack containing a decent sized bottle of water, a hat, suncream and snacks, and they are good to go.
Parents apply suncream before going to school and send kids in already wearing hats.
Teachers could make a short stop on the way and ask everyone to have a drink. Just to ensure everyone does drink. But obviously tell kids to drink throughout the day.
Kids top up suncream before walking back to school.
Refill bottles with tap water if needed.
Another short drink stop on the way back to school.
It's not rocket science.