On a recent trip to Ohio to visit my daughter and her family I got a request from her and a friend to "teach them to sew". Thankfully I got the request before I left home so I was able to bring my sewing machine and I had given my daughter one earlier. Her friend had a machine so we were all set. Before leaving home I gathered up some simple projects that I thought they would enjoy and would give them instant (almost) gratification. I figured that if I could get them hooked on at least one thing they would continue to sew after my short week there. It worked! They each made a pair of pillowcases from a pattern I got online. It's the one made with no raw edge seams. They also each made a 10 minute table runner and a small quilted bag and a gift card holder. They are hooked on sewing and maybe soon quilting. Got a call from them just a week or so ago and they were together doing more sewing.
I guess my suggestion is to start with something simple that can be completed in the length of time you have for classes so that they don't start out with a UFO.