Returning from spring vacation, Dowan McNair-Lee's students find their desks in neat rows, facing forward. For the previous seven months, the 8th graders had sat in clusters, facing one another, to facilitate discussion. But janitors used the break to ready the classroom for the year-end tests that are only two weeks away. The new arrangement is the backdrop for a changed tone in the classroom as well. The District of Columbia school system has chosen an aggressive and comprehensive approach to implementing the standards, making major investments in resources and professional development. But like most districts, it faces many challenges as it tries to turn its vision into changed practice in the classroom.