This project book, part of a set of materials written by the members of the Making Thinking Visible Project, reflects the discoveries of 30 elementary, high school, college, and community teachers' collaborative inquiry into students' thinking and the process of classroom observation and reflection. The document explains collaborative planning--a writing strategy that helps students develop a piece of writing by discussing key rhetorical considerations with a partner--and suggests ways that teachers may want to use this technique as part of the way they teach writing. The document has four sections: (1) Defining "The Making Thinking Visible Project"; (2) Introduction to Collaborative Planning; (3) Initiating Collaborative Planning: Some Practical Suggestions for Designing a Class; and (4) Classroom Inquiry: An Introduction to Research Based on Observation and Reflection. Objectives and goals, benefits and limitations, teaching strategies, teaching methods, and principles of collaborative planning are discussed in detail. Three figures are included; lists of the project members are attached. (PRA)