1 THE TEACHER EDUCATION AND LEARNING TO TEACH STUDY: AN OCCASION FOR DEVELOPING A CONCEPTION OF TEACHER KNOWLEDGE

embarked on a new research agenda: to investigate the relative impact of different approaches to teacher education on teachers ' knowledge, skills, and dispositions. In preparation for this ambitious investigation, the research staff faced the task of devising ways to track changes in teachers.2 Conceptualizing and developing instruments was difficult because experts do not agree about what teachers need to know and, thus, about what should be the focus of instruments designed to track teacher change. Some argue that teachers should learn a set of routines and skills applicable in just about any situation, irrespective of the subject matter or the learners ' backgrounds. Others contend that teachers need to understand a particular theory of learning. Still others insist that teachers need to know the values, normative social behaviors, and preferred communication styles of the pupils they teach. And some feel a good liberal arts education is really all teachers need. The particular challenge for the NCRTE researchers was to devise instruments that would track changes in teachers along a wide range of dimensions of teacher knowledge and also be sensitive to a wide variety of conceptions of what teachers need to know. This was critically important for the Center's research because the teacher education programs chosen for the Teacher Education and Learning to Teach Study were selected precisely on the basis of their differences. The programs represented varie