Prepare egg shells ahead of time so they will have time to dry completely. Crumble and dye the shells with food coloring. Give each child a sturdy card stock cut in half (8 1\2 X 5 1\2) with two holes punched in the top and a piece of string about 9 inches long. Let them print on the card in large block letters, "Don't Leave Your Room Without It!" Decorate the letters and the background using the colored shells like mosaic. The children should tie one end of the yarn in each hole to make a hanger.