I teach on a 1.5 hour per class block, and lately (this year), I've just been plowing right through a concept for the whole class. I tried something different yesterday that maybe I'll keep doing (or doing periodically).
Various comments and glances at tests have reiterated the fact that basic math skills are not as fresh and exciting as they could be: adding and subtracting positive/negative numbers, factoring, FOILing, etc. I don't want to stop class and reteach these things for a large block of time, but I don't want to ignore it. A few days ago, I discussed the +/- issue briefly. I showed them a potentially new trick. Then yesterday I wanted to see if it stuck.
Right in the middle of class I announced, "Pop Quiz" and handed out quarter sheets of scratch paper. Now my pop quizzes are just for their/my knowledge, and I don't record it. I put up 6 +/- problems, and they did it and they graded their own papers. I asked for a show of fingers on how many they got wrong. We moved on back to our regularly scheduled program, since there were low "wrong" numbers. This took all of 3 minutes (?), and it provided their brains a break from logic and proofs for a bit, and I'm SURE they were refreshed and ready to go again afterward :).
Maybe next time it will be a factoring break of 2 problems.