About the NAEP Science Assessment
NAEP Samples
The schools and students participating in NAEP assessments are selected to be nationally representative. The results from the 2024 science assessment at grade 8 are based on a representative sample of 23,000 eighth-graders from 600 schools who took the assessment either on a Microsoft Surface Pro tablet or Chromebook. Samples of schools and students are drawn across the nation from public schools and private 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 2024 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 digitally based assessment, 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). The assessment 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 SD and EL 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 2024.
In March 2010, the National Assessment 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 not 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 2024 science assessment at grade 8 were 89 percent (94 percent for public schools, 37 percent for private schools, and 87 percent for Catholic schools). In 2024, the school participation rates for private schools at grade 8 did not meet the criteria so their results are not reportable.
Weighted student participation rates for the 2024 science assessment at grade 8 were 88 percent (88 percent for public school students, 92 percent for private school students, and 92 percent for Catholic school students).
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. 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 the 2024 science assessment at grade 8 are reported for the nation.