National Center for Educational Accountability:

This report explores the possibility of reaching higher standards for all students in all schools and suggests the principles and practices for doing so. Of course, moving any school system from knowing what high-performing systems do, to doing what high-performing systems do is a complex process. Strong agreement about what high-performing systems do will begin to bring some order to that process.
One practice, which relates to the Framework theme of Curriculum and Academic Goals, is the pursuit of rigorous course content across a broad range of academic levels in high-performing schools. This includes higher expectations for the work of students characterized as “average” or “below average,” more aggressive efforts to enroll borderline students in advanced classes, and more frequent access to the school’s top teachers for average students. At Dr. Michael M. Krop Senior High School in Florida, educators said that the “culture of high expectations is applied to students at all performance levels, not just to the academically advanced.” Students in all academic courses expect homework assignments that require approximately two hours of time each day to complete for each class.

via Joanne.