Do you have time to have them practice without thread on paper first? Then you can get an idea of their confidence and ability before starting on the fabric. In a school project we did a simple 9 patch pot holder and it was pretty easy for most of us. Maybe you could do a square quilt with 9 blocks... 5 of them 9 patch and the other 4 solids. If you get on a roll you can have them do the simple appliqué in the solids, otherwise leave them blank.