Long-term trend NAEP measures student performance in mathematics and reading every four years. Last reported for 2008, it will be reported next for 2012.

Main NAEP assessments measure student performance in mathematics and reading every two years, most recently in 2011, and then in 2013. Other subjects, such as science, writing, and more, are also assessed.

Long-term trend NAEP has remained relatively unchanged since first administration (1971 for reading, 1973 for mathematics), although some changes that didn't affect trend reporting were instituted in 2004.

Mathematics focuses on numbers and numeration, variables and relationships, shape and size and position, measurement, and probability and statistics. Assesses basic skills and recall of definitions.

Students respond to questions in multiple-choice format; there are also a few short answer questions (scored on a two-point scale). Students are not asked to show or explain their work.

Reading features short narrative, expository or document passages, and focuses on locating specific information, making inferences, and identifying the main idea of a passage. On the average, passages are shorter in long-term trend reading than in main NAEP reading.

Students respond to questions in multiple-choice format; there are also a few questions requiring an extended answer (usually scored on a five-point scale).

Main NAEP assessments change about every decade to reflect changes in curriculum in the nation’s schools; new frameworks reflect these changes.

Mathematics focuses on numbers, measurement, geometry, probability and statistics, and algebra. In addition to basic skills and recall of definitions, students are assessed on problem solving and reasoning in all topic areas. 

Students respond to questions of several possible types: multiple choice, short answer, and extended answer. Constructed-response questions may be scored as correct or incorrect, or they may be scored on a multi-level scale that awards partial credit. Students may be asked to explain their answers or show their work.

Reading requires students to read fiction, literary nonfiction, poetry, exposition, document and procedural passages or pairs of passages; measures a range of reading skills, from identifying explicitly stated information, to making complex inferences about themes, to comparing multiple texts on a variety of dimensions. 

Students respond to questions of three possible types: multiple choice, short answer (called short constructed response and scored on a two- or three-point scale), and extended answer (called extended constructed response and scored on a four- or five-point scale).

Students are selected by age (9, 13, and 17) to represent the the nation and to provide results for student groups such as Black, Hispanic, White, and sometimes others, by gender, family income, and school location.

SD and ELL students are included using the same participation guidelines and with the same accommodations (as needed) in main NAEP.

Private school results are available when reporting criteria are met; there is no oversampling of private schools.

Students are selected by grade (4, 8, and 12). Students represent the nation and, in some assessments, their states or selected large urban districts. To provide state- and district-level results, far more students must participate than for national results only; these larger sample sizes permit even more detailed results.

The inclusion and accommodation treatment is the same for main and for long-term trend assessments.

Private school results are reported at the national level when reporting criteria are met, and sometimes private schools are oversampled to increase the information.

Long-term trend is assessed every four years, throughout the school year: in October through December for 13-year-olds, January through March for 9-year-olds, and March through May for 17-year-olds. See the schedule for all assessments (long-term trend as well as main NAEP).

Test booklets contain three 15-minute blocks of questions, plus one section of student questions concerning academic experiences and demographics.

There are no ancillary materials such as calculators or manipulatives.

Main NAEP mathematics and reading are assessed every two years (the odd-numbered years) at grades 4, 8, and 12. The other subjects are assessed less frequently, in the even-numbered years. The administration for all main NAEP subjects takes place from late January through early March.

Test booklets contain two 25-minute blocks, plus student questions concerning academic experiences and demographics.

There may be ancillary materials provided with the test booklets. Several subjects have, or will have, computer-based components.

National-level performance and how it has changed since the 1970s is reported using scores on a 0-500 scale. Long-term trend also reports descriptive performance levels (150, 200, 250, 300, and 350) that have the same meaning across the three age levels. There are no achievement levels to correspond with those used in main NAEP.

There are student questionnaires, but no teacher or school questionnaires.

Main NAEP has been reported since the 1990s for the nation and participating states and other jurisdictions, and since 2002 for selected urban districts. Performance and how it has changed over the past several years is reported using scale scores and achievement levels. Scores are reported using either a 0-300 or 0-500 scale, depending on the subject. The achievement levels reported are Basic, Proficient, and Advanced. 

Student results are reported in the context of the questionnaires given to the students' teachers and principals.