About the NAEP Science Assessment

The National Assessment of Educational Progress (NAEP) is a congressionally mandated project administered by the National Center for Education Statistics (NCES) within the U.S. Department of Education and is the largest continuing and nationally representative assessment of what our nation's students know and can do in select subjects. NCES first administered NAEP in 1969 to measure student achievement nationally. The NAEP science assessment measures students’ knowledge of three broad content areas—Physical Science, Life Science, and Earth and Space Sciences—and four science practices—Identifying Science Principles, Using Science Principles, Using Scientific Inquiry, and Using Technological Design. These four practices describe how students use their science knowledge by measuring what they are able to do with the science content. Results for grades 4, 8, and 12 are reported for the nation.

In 2019, the NAEP science assessments at grades 4, 8, and 12 transitioned from being paper-based assessments (PBA) to digitally based assessments (DBA). A multi-step process was used for the transition from PBA to DBA, which involved administering the assessments in both formats. Students were randomly assigned to take either the digitally based or paper-based assessment in 2019. The assessment results in this report are based on the combined performance of students who took the paper-based and digitally based assessments. The transition was designed and implemented with careful intent to preserve trend lines that show student performance over time. Thus, the results from the 2019 science assessments can be compared to results from previous years. Read more about the NAEP Digitally Based Science Assessment.

Samples, Inclusion, and Participation

NAEP Samples

The schools and students participating in NAEP assessments are selected to be nationally representative. The results from the 2019 science assessment at grades 4, 8, and 12 are based on a representative sample of 30,400 fourth-graders from 1,090 schools, 31,400 eighth-graders from 1,070 schools, and 26,400 twelfth-graders from 1,760 schools. Samples of schools and students are drawn across the nation from public schools, private schools, Bureau of Indian Education schools, and Department of Defense schools.

The results from the assessed students are combined to provide accurate estimates of the overall performance of students in the nation. Results for the nation reflect the performance of students attending public and private schools. Download the summary data tables via the link at the bottom of the page to see the national sample sizes for the 2019 science assessment.

Each school that participated in the assessment and each student assessed represents only a portion of the larger population of interest. The results are weighted to account for the disproportionate representation of some groups in the selected sample, including the oversampling of schools with high concentrations of students from certain racial/ethnic groups and the lower sampling rates of students who attend small schools. Read more about NAEP sampling and weighting in the NAEP Technical Documentation.

NAEP Inclusion

Assessing representative samples of students, including students with disabilities  (SD) and English learners  (EL), helps to ensure that NAEP results accurately reflect the educational performance of all students in the target population and are a meaningful measure of U.S. students' academic achievement over time.

To ensure that all selected students from the population can be assessed, many of the same accommodations that SD and EL students use on other tests are provided for those students participating in NAEP. Read more about accommodations available in NAEP. In the 2019 NAEP science assessment, accommodations were provided for both DBA and PBA. In DBA, some accommodations were provided by the test delivery system (e.g., extended time), while others were available outside of the test delivery system (e.g., breaks during the test). DBA also included a set of accessibility features, referred to as universal design elements, that were available to all students.

Even with the availability of accommodations, some students may still be excluded. Differences in student populations and in state/jurisdiction and district policies and practices for identifying and including SD and EL students should be considered when comparing variations in exclusion and accommodation rates. States/jurisdictions and districts also vary in their proportions of special-needs students. Download the summary data tables via the link at the bottom of the page to see the percentages of SD and/or EL students identified, excluded, and assessed in science in 2019.

The National Assessment Governing Board, which sets policy for NAEP, has been exploring ways to ensure that NAEP continues to appropriately include as many students as possible and to do so in a consistent manner for all jurisdictions and districts assessed and reported. In March 2010, the Governing Board adopted a new policy outlining specific inclusion goals for NAEP samples. At the national, state, and district levels, the goal is to include 95 percent of all students selected for the NAEP samples and 85 percent of those in the NAEP sample who are identified as SD or EL. Read more about the inclusion policy and how the percentages of students are calculated.

School and Student Participation

To ensure unbiased samples, NAEP requires that participation rates for original school samples be 70 percent or higher to report national results separately for public and private schools. In instances where participation rates meet the 70 percent criteria but fall below 85 percent, a nonresponse  bias analysis is conducted to determine whether the responding school sample is representative of the population, thereby introducing the potential for nonresponse bias.

Before replacing originally sampled schools that declined to participate with substitute schools, the weighted national school participation rates for the 2019 science assessment were 93 percent for grade 4 (97 percent for public schools, 50 percent for private schools, and 74 percent for Catholic schools), 91 percent for grade 8 (95 percent for public schools, 44 percent for private schools, and 71 percent for Catholic schools), and 84 percent for grade 12 (88 percent for public schools, 35 percent for private schools, and 55 percent for Catholic schools). In 2019, the school participation rates for private schools at grades 4, 8, and 12 and the school participation rate for Catholic schools at grade 12 did not meet the criteria, so their results are not reportable.

Weighted student participation rates were 94 percent at grade 4 (93 percent for public school students, 95 percent for private school students, and 96 percent for Catholic school students), 91 percent at grade 8 (90 percent for public school students, 94 percent for private school students, and 94 percent for Catholic school students), and 72 percent at grade 12 (72 percent for public school students, 77 percent for private school students, and 77 percent for Catholic school students).