Teacher gifts are hard because you really want to give them something useful. I've seen this idea of a "Teacher's Survival Kit" done before using a box, like a pencil box. I think it's a great idea because you can fill it with essentials that'll get used throughout the year: band-aids, post-its, aspirin, cold medicine, maybe even a little trial size hair spray?!
My version uses a drink carrier, specifically a Starbucks Frappucino drink carrier--perfect size! Smaller than a 6-pack carrier, so you won't have trouble filling it. And it gives the teacher easy and quick access to the contents.
To deocrate it, I wrapped the carrier in fun paper I had with double-sided tape; made up some embellishments, and tied a ribbon on the handle. I made up different color variations (because I'm so indecisive!) so if you want to make a kit of your own, you can download the label and apple circles here. You'll definitely earn an A+ for effort!