COVID-19: A contagious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). 

Elementary school: A school that has no grades higher than grade 8. 

English language learner: An individual who, due to any of the reasons listed as follows, has sufficient difficulty speaking, reading, writing, or understanding the English language so as to be denied the opportunity to learn successfully in classrooms where the language of instruction is English or to participate fully in the larger U.S. society. Such an individual (1) was not born in the United States or has a native language other than English, (2) comes from environments where a language other than English is dominant, or (3) is an American Indian or Alaska Native and comes from environments where a language other than English has had a significant impact on the individual’s level of English language proficiency. 

High school: A school that has at least one grade higher than grade 8 and no grade in K–6. 

High school completer: An individual who has been awarded a high school diploma or an equivalent credential, including a GED certificate. 

High school diploma: A formal document regulated by the state certifying the successful completion of a prescribed secondary school program of studies. In some states or communities, high school diplomas are differentiated by type, such as an academic diploma, a general diploma, or a vocational diploma. 

Middle school: A school that has any of grades 5–8, no grade lower than grade 5, and no grade higher than grade 8. 

National School Lunch Program (NSLP): Established by President Truman in 1946, the NSLP is a federally assisted meal program operated in public and private nonprofit schools and residential childcare centers. To be eligible for free lunch, a student must be from a household with an income at or below 130% of the federal poverty guideline; to be eligible for reduced-price lunch, a student must be from a household with an income between 130% and 185% of the federal poverty guideline. Student eligibility for this program is a commonly used indicator of family socioeconomic status. 

Postsecondary education: The provision of a formal instructional program with a curriculum designed primarily for students who have completed the requirements for a high school diploma or its equivalent. These programs include those with an academic, vocational, or continuing professional education purpose and exclude vocational and adult basic education programs. 

Scale score: Scale scores place students on a continuous achievement scale based on their overall performance on the assessment. Each assessment program develops its own scales. 

Socioeconomic status: Most data sources for this report use participation in the National School Lunch Program as an indicator of socioeconomic status.

HSTS: High School Transcript Study

IMF: International Monetary Fund

K–12: kindergarten through 12th grade 

LTT: long-term trend

NAEP: National Assessment of Educational Progress 

NASEM: National Academies of Sciences, Engineering, and Medicine 

NCES: National Center for Education Statistics 

NSB: National Science Board

NSLP: National School Lunch Program 

PISA: Programme for International Student Assessment 

S&E: science and engineering

STEM: science, technology, engineering, and mathematics 

TIMSS: Trends in International Mathematics and Science Study