The resource (beginning on page 15) gives excellent background information that derives the equation for the conservation of energy of a falling object. Using that background as a guide, the resource then has the students perform an experiment with a PASCO cart on a track that is pulled by a falling mass. The experiment asks the students to determine the kinetic energy of the cart and compare it to the gravitational potential energy of the falling mass. From their results, the students are asked to state if energy is conserved.