Research has long been clear that teachers matter more to student learning than any other in-school factor. Improving the quality of teaching is critical to student success. Yet only recently have many states and districts begun to take seriously the importance of evaluating teacher performance and providing teachers with the feedback they need to improve their practice. The MET project is working with nearly 3,000 teacher-volunteers in public schools across the country to improve teacher evaluation and feedback. MET project researchers are investigating a number of alternative approaches to identifying effective teaching: systematic classroom observations; surveys collecting confidential student feedback; a new assessment of teachers' pedagogical content knowledge; and different measures of student achievement. In this report, the authors investigate the properties of the following five instruments for classroom observation: (1) Framework for Teaching (or FFT, developed by Charlotte Danielson of the Danielson Group); (2) Classroom Assessment Scoring System (or CLASS, developed by Robert Pianta, Karen La Paro, and Bridget Hamre at the University of Virginia); (3) Protocol for Language Arts Teaching Observations (or PLATO, developed by Pam Grossman at Stanford University); (4) Mathematical Quality of Instruction (or MQI, developed by Heather Hill of Harvard University); and (5) UTeach Teacher Observation Protocol (or UTOP, developed by Michael Marder and Candace Walkington at the University of Texas-Austin). [For related reports, see "Gathering Feedback for Teaching: Combining High-Quality Observations with Student Surveys and Achievement Gains. Research Paper. MET Project" (ED540960) and "Gathering Feedback for Teaching: Combining High-Quality Observations with Student Surveys and Achievement Gains. Policy and Practice Brief. MET Project" (ED540962).]