Objective: Demonstrate plate tectonic principles, plate boundary interactions and the geometry and relative motions of faulting of geologic layers using 3-D foam models. The foam models aid in visualization and understanding of plate motions and faulting because the models are three-dimensional, concrete rather than abstract descriptions or diagrams, can be manipulated by the instructor and the students, and the models can show the motions of the plates and faults through time in addition to the three-dimensional configuration of the plates or layers. The fault and plate boundary models shown here illustrate relatively simple motions and geologic structures. Although these models are accurate representations of real Earth faulting and plat...