We’ll ask an expert, or even a student, to “tell me what you know” about some topic. But now I’m thinking it makes more sense to ask people to tell us what they don’t know.
Why? Consider your understanding of a particular topic to be divided into three parts:
1. What you know.
2. What you don’t know.
3. What you don’t know you don’t know.
If you ask someone about 1, you get some sense of the boundary between 1 and 2.
But if you ask someone about 2, you implicitly get a lot of 1, you get a sense of the boundary between 1 and 2, and you get a sense of the boundary between 2 and 3.
As my very rational friend Ginger says: More information is good.