Describes an apparatus (called the "Rainbow Cup") used for demonstrating the colored rings produced by constructive interference in soap films. Discusses construction of the Rainbow Cup and gives hints for its use in the classroom, especially in relation to classroom humidity. (JM)

Students must understand the fundamental process of convection before they can grasp a wide variety of Earth processes, many of which may seem abstract because of the scales on which they operate. Presentation of a very visual, concrete model prior to instruction on these topics may facilitate students' understanding of processes that are largely…