Focus on classroom teaching practice has never been greater than in recent years. As part of the commitment states and jurisdictions have made under federal programs such as Race to the Top and the Teacher Incentive Fund, and in seeking waivers from the constraints of No Child Left Behind, states and districts have committed to change policies and practices in all aspects of teacher evaluation. A large number of observation instruments have been developed to structure evaluation of the skills of teachers in the classroom and support actionable feedback. These instruments vary in their philosophy of instruction, dimensions of teaching that are valued, and specificity of application to particular content areas or grade levels, among other aspects. [Abstract taken from Introduction]