The great gorilla jump is an activity designed to allow calculus students to construct an understanding of the structure of the Riemann sum and definite integral. The activity uses the ideas of position, velocity, and time to allow students to explore familiar ideas in a new way. Our research has shown that introducing the definite integral as area under a curve "first" does not give students the foundations they need to be able to solve more difficult word problems involving definite integrals. Thus, this activity uses familiar ideas to build the foundations needed for understanding Riemann sums and definite integrals.