In recent years, naturalistic studies of planning have shown the "hidden side of teaching," pictures of the ways teachers think before and after they enter the classroom. Few, however, have shown how prescriptive planning models impact on teacher thought and the classroom environments the they create; and none has looked at the impact of prescriptive planning models on preservice teacher thought. The purpose of my study was to create ethnographic descriptions of two preservice teachers’ thoughts and of the classroom environments they created. The major difference between the two participants was the prescriptive planning model used. One used a rational means-end planning model -- the model most commonly taught to prospective teachers when they are first introduced to unit planning. This model encourages the teacher to develop a written unit plan with a rationale, objectives, activities, and evaluation standards prior to the teaching of a lesson or set of lessons. The other preservice teacher used a recently developed recursive planning model that encourages brainstorming, design, and reflection based on a list of educational design variables that research has indicated have an impact on educational environments. My ethnographic findings reveal that the use of both planning models impacted on preservice teacher thought and on the classroom environments they created in terms of: 1. the quantity, quality and content of the planners’ preactive and postactive thought, 2. the quantity of unplanned decisions that the planners made while teaching, 3. the overall organizing principle of their classroom environments, and 4. the way preservice teachers defined and practiced planning. / Ed. D. / incomplete_metadata