I like to keep some history. It's useful, and fun to go back to. I've been using acid-free Strathmore sketch books (various sizes) for about 25 years. Usually

I like to keep some history. It's useful, and fun to go back to. I've been using acid-free Strathmore sketch books (various sizes) for about 25 years. Usually with a fountain pen, but that's just an affectation. Small, hand-sized notebooks for small ideas. Paperback-book sized notebooks for meeting notes. 8 1/2 x 11 inch notebooks for general engineering. The friend that I stole this little system from said that he had a coffee-table-sized book at home that he'd never used, because he'd never had an idea that big. :-) When I join a project and I'm in "sponge" mode, I usually copy down APIs and make class diagrams. There's something about muscle memory and the act of hand-copying that makes it easier to remember details of the system I'm learning.