I think a lot depends on what equipment will be available for your class. Will they each have a sewing machine, etc?
If they will have a sewing machine, I vote for the travel tissue cover. They can easily make 2 or 3 of them in that hour. One to keep and two to give as gifts. You could have all of the fabric cut ahead of time and have them pick out which colors they want to make. Get a package of the tissues so they can go home with the complete item. I work at 3 different schools during the week and made enough of these tissue holders for all of the ladies in each of my offices. They loved it.