Four full days of classroom instruction, devoted to the modeling of effective curriculum integration, were designed for preservice elementary school teachers. The unit was the result of a conviction on the part of teacher educators that children learn best when learning is not separated into forty-minute periods of math, social studies, language arts, and science, but rather combined into a more meaningful, holistic experience. To demonstrate to the education students the feasibility of this kind of teaching, the unit integrated all of the curricular areas into a "methods block." The unit was based on an episode of Carl Sagan's television series, "Cosmos." The episode selected was "The Harmony of Worlds," which tied together the whole fabric of crucial events within a particular historical period. The motivation for, planning, and execution of the unit are discussed and each day's activities are described. Factors which led to its success are considered. (JD)