Very simple and short video from MinutePhysics! It goes by fast — only 18 seconds long. Watch it a few times, and pause the video at the end when words are on-screen. We’ll set this one up a bit. During the summer, when you’re inside… people outside generally can’t see you … when you’re… inside! Yet – when winter comes and it turns dark outside, they can see you plane as day — sitting… inside! Now watch this — watch it again — and if you want to “slow down the learning”, take this one to science class!