Igloos are cool. You can easily build a milk jug igloo with some planning, lots of milk jugs and hot glue.    For example, the children in Classroom 1 at Midland Christian School (Midland, Michigan) built the 428-jug igloo shown here after collecting (and cleaning) milk cartons for about 3 weeks. This medium-sized igloo is large enough to hold about 8 to 10 kindergardeners or first graders.