The phases of learning, as ordered by age:
Teenager: I know the answer.
College student: I think I know the answer.
University Student: I can prove there is an answer.
Post-graduate Student: I can prove there is an answer that may or may not be correct.
Parent: It’s the answer because I said so.
Working professional: I might not know the answer, but I know how to find it.
Business person: I know the answer, but it’ll cost you to get it.
Retiree: I used to know the answer, but now I don’t care.
Grandparent: I bet my son/daughter knows the answer.
Old person: What was the question?
Dead person: …