Need a suggestion for my knitting class.

Hi there. I teach a knitting class for an art group in my community. We have already done basic knits, purls, cast on, and bind off. For my next class I want to teach increasing, decreasing, and knitting-in-the-round within the same project. It’s only a two hour class so the project must knit up quickly. I planned making a knitted winter headband using bulky yarn but I’m having difficulty keeping it…

1. uncomplicated
2. same amount of stitches for every round
3. being stretchy (to fit snug around the head)

I am willing to do something other than a headband but am stumped to think of something else that can be finished in time. Any suggestions?