We found this on one of our favorite sites — “MinutePhysics”. This one is just plain neat! If you are a “calendar watcher” – and prefer the long days of summer vs. the long dark days of winter — you’ll really appreciate this. It’s short — and does a great job of explaining it simply. If you don’t understand it — or have questions — this is a GREAT one to have your science teacher talk about. In a fun 20 minute conversation in class, you’ll learn something fun you’ll remember for life — to tell you kids and your grand kids!