"I don't know" can be quite liberating, and open the door to finding out more.
Maybe we need to practice saying it a few times.
Obviously in situations when we think that might actually be true.
When you're learning something new, which should occur in our context here quite frequently, take on that "beginner's mind".
And with that, one would err towards not knowing.
Moving away from this extreme, other potential door openers could be:
I don't know *enough*.
I'm not sure yet.
Tell me more!
What would be good for me to know?
"Yet" seems pretty powerful as well, implying intention to figure out.
The beginner's mind(set) is closely tied to trying out and being ok with making mistakes. Even consciously.