With this coming semester looming or, perhaps, here, it's a good time to do this one again. I have a schtick that I do before every class where I let students ask any question at all, auto mechanics to quantum mechanics. When I started the Playground years ago, some former students asked if I'd bring the exercise on-line, so here it is. If there is a question you've always wanted to ask, here's your chance. We'll discuss as many as possible next week. Fire away.