I’m developing a record system, cobbled from bits and pieces garnered here and there. I use manila file folders for each class (from David Allen’s excellent GTD). This holds every thing I need for today’s class, plus the previous class (e.g. homework I collected, handouts I used, plus the 1-page record sheet I use). Everything prior to 2 sessions ago goes in a larger, heavier 32-ring file.
All this is heavy to carry around, so I’m experimenting with a different system using 3×5 index cards, called Pile of Index Cards (or PoIC) by hawkexpress, who’s done an amazing job with his bilingual wiki. This is much more than a class record system, but I’m tweaking it for my own purposes. The index cards are much lighter, and I can just about fit a 90-minute class record onto 1 side of 1 card (and if it won’t fit, I splurge and use 2 cards). Plus, they’re fun to use.