The goal of this article is to advance an ecological theory of knowing, one that prioritizes engaged participation over knowledge acquisition. To this end, the authors begin by describing the environment in terms of "affordance networks": functionally bound potentials extended in time that can be acted upon to realize particular goals. Although there may be socially agreed-upon trajectories specifying the necessary components of a network activated for realizing a particular goal, the particular network engaged by an individual is dependent on adopted intentions and available "effectivity" sets, the attunements and behaviors that an individual can enlist to realize an affordance network. Thus, to help clarify the challenges of connecting learners to ecological systems through which affordance networks are activated, the authors use the term "life-world," which refers to the environment from the perspective of an individual. Building on their characterization of affordance networks, effectivity sets, and life-worlds, the authors offer an ecological focal point for curricular design. (Contains 4 notes and 1 figure.)