On?

Alex has mostly figured out the concept of on. She knows she always wants ceiling fans on. She always wants the tv on (even if she always leaves the room about a minute later). But now she wants thing on that don't go on, like, say, dinner. On the table, yes, but just on......hmm, no idea how to pull that one off. Train on, yes I get it. Book on, well, ok, I suppose. I guess on is a good thing, and off is bad. Makes sense to me. :)