In high school math ,we usually had a stanupin the beginning of every lesson. Basically th entire class on their feet answering rapid fire questions from the teacher , usually some stuff that had been taught in the previous lesson. No calculator/notes just doing math in your head to get to sit down and start the class. Gnereally sucked when we were going through it , looking back though made digesting the material easier as you had to know, not just cram or hope for a calc or scrap paper to caluclate with.

So basically a oral pop quiz for math. i think could work well to complement homeworks by making sure the material as taught is actually inside the students heads.

you can only do things that suck when attendance isn't optional.