Cover the cupcakes with yellow frosting and allow them to sit for an hour before decorating. Dab each red Skittle or M&M with a bit of green frosting for the apple's leaf, then set them aside.
Put a tablespoon or two of white frosting into a small plastic bag for piping. Cut a very small hole in a corner of the bag, twist the top of the bag closed, and secure it with a rubber band or twist tie. Piping the frosting gently out of the hole, write messages on the chocolate-covered graham crackers. Leave space at the bottom of the cookie, where it'll be stuck into the cupcake.
Cut a groove in the cupcake's frosting with a knife, then fit a blackboard into the groove. Add one Skittle or M&M apple and a piece of Good & Plenty chalk, as shown.
