Be sure to have your course outline available to the prospective students so they know what to expect, including materials they need to bring (pins? scissors? rotary cutter/mat? iron? machine? thread?). And I'd have whatever extras I could scrounge up with me for the ones who will come with completely different things than you suggest :)
Personally, if the course was to learn to quilt and I ended up making pot holders, that wouldn't make me happy.
If the course is intended for students who haven't sewn at all, they'll need to learn about cutting precisely and sewing the 1/4" seam, and pressing. So again, a pot holder wouldn't give me enough practice on seams.
What about having a number of strip sets ready to put together to figure out how to do the 1/4" seam - 3 strips, six" long, 2" wide. You could end up with dozens of strip sets ... and put them together into a wall hanging (without correcting anything!) or sub-cut into different shapes to show how much you can do with just strip piecing (tube quilts, rail fence, there are tons of books on this!).
I like your idea about incorporating other sewing methods into the class - but rather than 'mending', sew the button on to decorate an embroidery square!
I'd also suggest putting together a list of resources for the students - local library for books/magazines, any local guilds?, local quilt shops, websites (quilter's cache, quiltville, this board!)
Good for you for sharing your passion, good luck with the class!