Begin in a semisquat stance with shoulders perpendicular to the stairs and the weight on the upstairs leg.
Keep the weight shifted into the steps, drop back one step with the downside leg, and, with immediate extension of that leg and knee, drive off the upside leg, quickly bound upward and inward two or three steps. Continue this drop one, bound two or three up for 8 to 12 repetitions; then repeat facing the opposite direction.