I've had a few different clay projects going on in 4th grade. At one of my schools we decided to make clay cupcakes. I've made these before with the silicon cupcake holders using model magic, salt dough, but this round we used air dry clay. It's the perfect clay project to do as the year winds down as it is SIMPLE and the kids love it. We had just finished another project where we studied Wayne Thiebaud so it was also a good extension of that. At the particular school where I did this lesson I have two sections of 4th grade. One class did such a nice job of following directions and helping each other out (whereas the other did not) they were rewarded with "sprinkles." Through trial and error I found a method that works! I was originally going to coat with epoxy, but I didn't have the time and want to spend the extra cash on that.
I first coated with the E6000 Spray Adhesive, sprinkled the sprinkles on top, then sprayed the adhesive again. I let that dry for maybe 20 minutes and went over with the clear coat. To my surprise no colors ran and they stick! I used a combination of the long soft sprinkles and the tiny circles. They both stick fine, but because of the softness of the longer sprinkles some of them will get smashed when picked up. So if you're going to try (or if I do it again sometime) I would suggest the smaller sprinkles.