On our way home from school today my 6 year old started rubbing her hands together very quickly. Soon she says "Mommy, I'm making friction. When you rub two things together very fast they make friction." Of course I have to take this opportunity to find out exactly how much she knows about this subject so I ask, "What does friction create". She replies (without any hesitation) "Heat". I ask her where she learned about friction because I know she doesn't have science this week (they rotate through specialists at her school from one week to the next). She tells me that she learned about it in science class (a couple of weeks ago). I'm a very proud parent.