Learn how to build an icy model of a comet, complete with shooting jets. This activity provides an opportunity for students to make observations, discuss changing states of matter and demonstrate measuring skills. Materials 5 pounds of dry ice - finely crushed Insulated container to hold the dry ice Thick gloves to handle the dry ice (check at online chemistry stores or hardware stores) Goggles Mallet to crush the dry ice Large plastic bowl Towel or pillowcase (it will get very dirty) Several l