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A simplified geometric model captures essential dynamics of stone skipping and allows easy computation of realistic stone trajectories under a variety of conditions. The model describes idealized collisions of flat, spin-stabilized stones with water, in which the water exerts sufficient reactive force on the stone to completely stall motion normal to the stone’s bottom surface. Motion parallel to the stone’s bottom surface remains unchanged. The necessary computations, including vector forces and accelerations, work and energy, algebra and trigonometry, are understandable by first year students of classical Newtonian physics. Comparison of this highly simplified theory with suitable experiments provides an interesting organizing theme for project based learning.