When I refrigerate overnight ingredients (like sugar cookie dough/above left, or chocolate chip cookie dough/above right), I group the containers by class and nestle them in the box lids. That way when it's time to set up, I only have to pull out one box rather than four or five bowls. The dimensions of the lid fit the depth of a typical refrigerator perfectly, and the sides keep what I'm carrying from sliding off.
I have a kid in my third hour who writes about poop a lot. You've probably had a kid like this yourself, so don't judge : ).
The lids are also good for supplies that you only use on occasion. For example, this year I've decided to store the hand mixers together outside of the student kitchens. Outside of the baking unit they really don't get used much, they take up room, the cords get tangled, and so on. I also always do a quick check of all the mixers before a lab when we haven't used them in a while (make sure the beaters still fit well, the motors are running, etc). This is much easier and quicker to do when they are all together, rather than having to go kitchen to kitchen.
When we do need them, I just set the box lid out on the table with the ingredients and the kids grab one. It's also handy that it's easy to inspect the mixers for cleanliness when they turn them back in, rather than when they surreptitiously stuff them in a drawer.
More on copy paper box lids - and the boxes themselves! - later...