I think when my kids get home EARLY from school today, I'll have them mow the lawn. They'll be outside anyway. That's the first place they go when there's an early out for heat.
And really it doesn't affect me much either way since my job is at home but for parents that work, it must be a huge inconvenience.
My generation and most likely those before me, never got out early because it was too hot. We usually did afternoon classes outside in the breeze and we turned on fans and drank lots of water. Then we went to football/volleyball practice and then home to do chores. I've heard all the arguments for the early out but really none of them are legitimate. I am sure that somewhere in a third world country or a war torn country, children and teachers are wishing they could attend school all day...heat or not.