Prompted partially partly by this highly recommended episode of This American Life, I've been thinking a lot recently about the soft skills of learning. In this case alertness.
One of the reasons I'm such of advocate of games and puzzles in the classroom is the fact that they help cultivate a state of alertness. If you can get students in the habit of looking for patterns in a math puzzle, they'll probably keeps looking for patterns and underlying structures when they open their math books.
O T T F F S S E... is one of my favorites. The question is what's the next letter in the sequence It can completely stump a Ph.D. in mathematics but if you approach it right the answer should hit you immediately.