Watch out for the black rubber mats at the playground.

Usually there is a sprinkler and the kids go bare foot. 
On hot days the rubber sits there and absorbs solar energy, it gets hot.

It gets so hot that it gave a toddler third degree burns on his sole.

Please watch your kids, and get them rubber shoes that they can wear in the water, "Water Shoes" 

This happened to my little girl.  A neighbor had a pool in the backyard, and one of those metal wedge shaped doors that lead tho the basement.  It was painted black.  My friend's daughter had shoes on and ran up the thing, and my little girl followed, she was 2 and half at the time.  About 3 seconds later she starts screaming, and squatting flailing her arms near her feet.  I was in the pool with my son and my friend.  I jumped out and got her in seconds.   I was so fast there were no burns.  My daughter's feet was a little pruned up from the water so this I think saved her from a burn.  The reason I was so fast, the same thing had happened at the park with the rubber mats weeks before.  The kids don't know what to do because where ever they step it's super hot.  So they stand there and scream.  When it happened at the park, I ran to her, but was perplexed to what was hurting her.  She was ok, because it was early in the day and the rubber had only so much heat. 

 Something reminded me of it, so I did not hesitate to jump out of the pool, but a few seconds  might be the difference between a burn or not.

Please be careful.  It's true black things absorb energy and get hot.

Antonio