I already know _______, so please tell me (something other than what they already “know”).
Here’s the thing: Just because you know something, doesn’t mean you don’t need to hear it ever again. It actually means you need to hear that even more than the stuff you don’t know. Do you remember every single piece of information you’ve ever received? No, you remove the stuff that you’ve been fed over and over and over again. And you really remember the stuff you’ve physically done, combined with and applying the knowledge.
As I’ve stated before, you don’t know anything until you’ve lived it — in other words, you’ve applied it in your real life and know exactly how it feels to do (not watch, not talk about, not read) it. And even then, you need to keep hearing it and reinforcing it and re-learning it to deepen your “knowing”. On top of all that, you must apply the knowledge — repeatedly — to have the real, transferable value: Experience.
If you’ve only done something once, there aren’t many people whom you can educate on the subject. When you’ve done it 100 times, you have probably seen many variables, which means you can assess a wide range of circumstances other people face.
So if there’s something that you think you “know”, good. Know it some more, apply it, and repeat. Your memory is not that good.