阅读Passage l，完成21题。
Passage 1
In recent years, however, society has come to understand the limitations of schools that merely sort and rank students. We have discovered that students in the bottom one-third to one-half of the rank order —plus all who drop out before being ranked--fail to develop the foundational reading, writing, and mathematical proficiencies needed to survive in, let alone contribute to, an increasingly technically complex and ethnically diverse culture. So today, in asking schools to leave no child behind, society is asking that educators raise up the bottom of the rank-order distribution to a specified level of competence. We call those expectations our"academic achievement standards". Every state has them, and, as a matter of public policy, schools are to be held accountable for making sure that all students meet them.
To be clear, the mission of sorting has not been eliminated from the schooling process. For the foresee-able future, students will still be ranked at the end of high school. However, society now dictates that such a celebration of differences in amount learned must start at a certain minimum level of achievement for all.
The implications of this change in mission for the role of assessment are profound. Assessment and grad-ing procedures designed to permit only a few students to succeed ( those at the top of the rank-order distribu-tion) must now be revised to permit the possibility that all students could succeed at some appropriate level.
Furthermore, procedures that permitted( perhaps even encouraged)some students to give up in hopelessness and to stop trying must now be replaced by others that promote hope and continuous effort. In short, the entire emotional environment surrounding the prospect of being evaluated must change, especially for perennial low achievers.
The students' mission is no longer merely to beat other students in the achievement race. At least part of their goal must be to become competent. Teachers must believe that all students can achieve a certain level of academic success, must bring all of their students to believe this of themselves, must accommodate the fact that students learn at different rates by making use of differentiated instruction, and must guide all students toward the attainment of standards.
The driving dynamic force for students cannot merely be competition for an artificial scarcity of success.
Because all students can and must succeed in meeting standards, cooperation and collaboration must come into play. The driving forces must be confidence, optimism, and persistence--for all, not just for some. All students must come to believe that they can succeed at learning if they try. They must have continuous access to evidence of what they believe to be credible academic success, however small. This new understanding has spawned increased interest in formative assessment in recent years.