Achievement levels: Achievement levels, which are set through a National Assessment Governing Board process, define what students should know and be able to do at different levels of performance. In the National Assessment of Educational Progress (NAEP), the achievement levels are Basic, Proficient, and Advanced. The definitions of these levels, which apply across all grades and subject areas, are as follows:

• Basic: This level denotes partial mastery of prerequisite knowledge and skills that are fundamental for proficient work at each grade.
• Proficient: This level represents solid academic performance for each grade assessed. Students reaching this level have demonstrated competency over challenging subject matter, including subject-matter knowledge, application of such knowledge to real-world situations, and analytical skills appropriate to the subject matter.
• Advanced: This level signifies superior performance.

The percentage of students at or above Proficient includes students at the Proficient achievement level and at the Advanced achievement level. Similarly, the percentage of students at or above Basic includes students at the Basic, those at the Proficient, and those at the Advanced achievement levels. See also supplemental note 4.

Alternative schools: A public elementary/secondary school that (1) addresses needs of students that typically cannot be met in a regular school, (2) provides nontraditional education, (3) serves as an adjunct to a regular school, or (4) falls outside the categories of regular, special education, or vocational education. Some examples of alternative schools are schools for potential dropouts; residential treatment centers for substance abuse (if they provide elementary or secondary educa­tion); schools for chronic truants; and schools for students with behavioral problems. About 7 percent of schools in the Common Core of Data (CCD) files are alternative schools.

Associate's degree: An award that normally requires at least 2 but less than 4 years of full-time-equivalent college work.