By Catherine Miles Grant, Barbara Scott Nelson, Ellen Davidson, Annette Sassi, Amy Shulman Weinberg, Jessica Bleiman. This 30-hour course uses classroom videotapes as a basis for considering issues in classroom observation and pre- and post-observation conferences with teachers. It seeks to make possible better alignment between supervisory practices and the changes that are taking place in mathematics classrooms guided by the NCTM's Principles and Standards of School Mathematics. It provides administrators with the opportunity to learn to attend to the mathematical essence of a lesson and to think about what one might productively talk with teachers about in pre-and post-observation conferences. Lenses on Learning.