To teach swimming, coaches take novices through the component skills in progressive stages. The first lesson takes place out of the water, at the side of the pool, where the novice learns the arm stroke and the leg stroke separately. Then the novice gets into the shallow end of the pool and practices the arm strokes and leg strokes, still separately, but now with training equipment — flotation devices, kick boards and the rungs of a ladder — to develop the skills further. As the training progresses, the novice puts aside the equipment and swims, first in the shallow end of the pool, then the deep end, and finally, in a lake or ocean. The fundamental aspect of this approach is to deconstruct the basics and then to reconstruct them progressively. It works in swimming — as it does in all sports — and it works in presentations.