Teach them basic steps of crocheting and maybe make a scarf as a first project to give to homeless people. You can also make cards to be sent to the troops overseas.
Sewing with plastic or blunt needles around fabric in different shapes with yarn and stuff shapes before closing. Plastic canvas with large holes can also be used.
Crafts that include glitter make messy but satisfying projects for an elementary aged Sunday school class. They also like making paper mache objects by covering blown up balloon with the goo, then letting it dry and painting it afterwards. Making christmas balls in December is always fun for this group.