What to do when it's so hot outside you can barely breathe?
Ice play! I filled my freezer with different sized containers full of water to make ice. Then I piled them into a trough to play with. I found that 2L ice cream container sized blocks of ice lasted the longest/best.
It was so cooling on hot skin, and is a great jumping board for discussions.
And even when the ice melted ("But, Erin, where did the ice go???") we still had ice cold water to splash in.