One of the smartest people I know also asks the dumbest questions.
She finished her master's degree when I finished my bachelor's. We are the same age, started in the same field at the same time, both qualified for full rides at our respective schools, and are hard workers.
Furthermore, in addition to being brilliant and having tremendous perseverance, she also has an intense form of dyslexia. With years of remediation, she managed to reach the 3rd percentile nationwide for reading ability. And yet, she earned her master's in engineering by age 23.
This piqued my curiosity: how did she do that?
During undergrad, she spent a couple of unplanned days with me. She was flying home to Chicago after an interview in California. Chicago's weather dashed any hopes of landing a plane, so she looked at her options and decided it would be fun to be stranded near me (agreed!).
Being an impromptu visit in the middle of the week, I still had all of the classes, homework and such that made up my life at the time, so she tagged along. (There may have been a bar trip or two in between classes. I shall neither confirm nor deny.)
My main memory of Emily on this trip was the two of us sitting in one of my classes, attentive to the lecture, and her hand shooting up. But where Hermione Granger would be volunteering an answer, Emily was asking questions. The kind of questions that I was taught were too embarrassing to ask. The types of questions that show you missed something in the lecture, that you failed to do the reading before class, or might (gasp! egads!) be dumber than the person sitting next to you.
And she asked. And she asked. And she kept asking until she understood. And then we moved on. And when she didn't fully comprehend something, that hand went straight back up, and you'd better believe we weren't going ANYWHERE until she knew what was happening.
And this, my friends, I believe to be the secret to her success. Where I would make a mark in my notes to come back and look something up (and as often as not forget to do so), she asks questions.
For me, consulting a book is trivial. I read scores of them each year. It is as easy as breathing. For Emily, consulting a book is an effort hard enough to make any possible momentary embarrassment of admitting ignorance or disrupting a class minor in comparison. She can spend two minutes now or struggle for who-knows-how-long later. So she asks. And she asks. And she gets answers.
From Emily, I learned one of my most powerful tools: Ask questions, even stupid ones, until you understand.
And once I started doing this, I learned that, more often than not, if someone can't explain a concept, it's not you that is failing to understand, but they who are failing to explain.