Lock-in idea: Baptismal remembrance bowls for the kids to make and take home. With a bigger lump of clay you can use an elbow or knee in place of a thumb - my mom used that method to teach my kids and they loved getting muddy ;
Students began with a ball of clay which they stuck their thumbs into to form pinch pots. They then took their pot, turned it on its side, scored and slipped features onto the pot to create creatures. This was a great creative outlet for the kids.