When you're a teacher, it doesn't matter what you know.
It doesn't matter what you've accomplished.
It doesn't matter how much you've studied or how many degrees you have.
It doesn't matter how often you've been published or how many prizes you've won.
It doesn't even matter if you say what you know out loud.
What matters? Your ability to teach.
You could possess life-changing knowledge. But, if you can't teach it in a way that others can understand and learn it, then none of it matters.