I've felt for a long time that writing is learning. For me it definitely is - I need to structure and express my thoughts before I really feel like they are mine, and not just ideas or whims.
In high school I used to summarize and re-summarize my notes over and over until the biology text book was in my brain. My dad used to say that information flowed from the tip of his pen, up his arm, and into his brain. There is definitely something to that, isn't there?
It was wonderful to find this article on Ness Labs about the generation effect:
Yay, science! Yay, validation!