As a student, asking questions and feeling safe to say "I don't know" are key to accessing new knowledge or skills. Most adults, however, are uncomfortable admitting they lack understanding because of the fear of being perceived as weak or unintelligent (I believe this is one of the reasons "you can't teach an old dog new tricks" is not as outdated an idiom as we might want to believe). I am no exception-- I hate saying "I don't know" so much, I will say almost anything else to avoid those words coming out of my mouth.
Learning a new skill as an educated adult comes with its own set of unique challenges, one of which is the assumption of others that you know a lot more than you actually do. One preconceived notion I have encountered as I have been learning HTML/CSS and now Javascript looks something like this: "She's 35 and has a college degree and a decent vocabulary-- she must understand me when every other word out of my mouth is jargon or an acronym related specifically to programming!" On top of believing this misconception, most experts have been working in their field for so long, they have completely forgotten what it feels like to be new, overwhelmed, and pretty damn sure you are going to fail.
The skill I have struggled the most with over the last ten months of studying is saying "I don't know." Though I've practiced saying it dozens (fine--hundreds) of times, I still cannot utter it without some internal debate first: "Could I fake this one?", "Maybe I can just google it later?", "I have already asked 4 questions in the past ten minutes-- what if I am annoying this person?", etc...
With abundant practice, however, comes sporadic moments of clarity; the proverbial lightbulb that goes on over my head as I realize there was a lesson in that last exchange. I tweeted as many of those lessons as I could recall, as a mini-twitter class I called "#idk101".