This qualitative, ethnographic study documented an upper primary school teacher's thinking as she planned to integrate a block play center into her classroom. Data was collected through a series of seven interviews in May, July, and August. Other methods of data collection included journal entries, stimulated recall, drawings, pictures, and notes from planning sessions. Analytic induction was used to synthesize and reduce the data set into codifiable categories indicative of content or thinking process. Analysis indicated that thinking and planning during the studied period were more mental than written, and were more cyclical than linear. Dilemmas surfaced and blocked decision making, and a period of low self-confidence interfered with the teacher's progression of decision making. The report calls for further investigation of teachers' thinking. (MM)