The needs of the teacher who seeks successful practical action are different from the needs of the scientist seeking truth. Distinctions made in action science bring out this difference. Action science emphasizes an integration of personal knowledge and social discourse along with objective data in cycles of planning, acting, and fact-finding about the results of the action. Practical ways for teachers to implement these features are discussed. In particular, methods of making it easier to obtain objective data by means of self-recording are presented in some detail. Two examples of field projects in the first grade mathematics illustrate how this works. (The first example presents a record that justifies keeping and repeating one of the teachers' strategies. The second example presents a record that indicates a change was needed and how the change turned out.) (Author/YP)