Advanced Placement (AP): Courses that teach college-level material and skills to high school students who can earn college credits by demonstrating advanced proficiency on a final course exam. The College Board develops curricula and exams for AP courses, available for a wide range of academic subjects.

Blended learning: Any time a student learns at least in part at a supervised, traditional school location away from home and at least in part through online delivery with some element of student control over time, place, path, and/or pace; often used synonymously with “hybrid learning.”

Distance education: A mode of delivering education and instruction to students who are not physically present in a traditional setting such as a classroom. Also known as “distance learning,” it provides access to learning when the source of information and the learners are separated by time and/or distance.

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

Eligibility for National School Lunch Program: Student eligibility for this program, which provides free or reduced-price lunches, is a commonly used indicator of family poverty. Eligibility information is part of the administrative data schools keep and is based on parent-reported family income and family size.

English language learner: An individual who, because of any of the following reasons, has sufficient difficulty speaking, reading, writing, or understanding the English language 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 an environment where a language other than English has had a significant effect on the individual’s level of English language proficiency.

GED certificate: This award is received after successfully completing the General Educational Development (GED) test. The GED program, sponsored by the American Council on Education, enables individuals to demonstrate that they have acquired a level of learning comparable with that of high school graduates.

High school: A school that has at least one grade higher than 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 5, and no grade higher than 8.

Online learning: Education in which instruction and content are delivered primarily over the Internet.

Organisation for Economic Co-operation and Development (OECD): An international organization of 34 countries headquartered in Paris, France. The member countries are Australia, Austria, Belgium, Canada, Chile, Czech Republic, Estonia, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Israel, Italy, Japan, South Korea, Luxembourg, Mexico, the Netherlands, New Zealand, Norway, Poland, Portugal, Slovak Republic, Slovenia, Spain, Sweden, Switzerland, Turkey, United Kingdom, and United States. Among its many activities, the OECD compiles social, economic, and science and technology statistics for all member and selected nonmember countries.

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.

Remedial courses: Courses taught within postsecondary education that cover content below the college level.

Repeating cross-sectional studies: This type of research focuses on how a specific group of students performs in a particular year, then looks at the performance of a similar group of students at a later point. An example would be comparing fourth graders in 1990 with fourth graders in 2011 in NAEP.

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.

Key to Acronyms and Abbreviations

ACGR: adjusted cohort graduation rate

AFGR: averaged freshman graduation rate

AP: Advanced Placement

CRDC: Civil Rights Data Collection

CREDO: Center for Research on Education Outcomes

ECLS-K: Early Childhood Longitudinal Study-Kindergarten

ESSA: Every Student Succeeds Act

GED: General Educational Development

HSLS: High School Longitudinal Study

IB: International Baccalaureate

IEA: International Association for the Evaluation of Educational Achievement

K–12: kindergarten through 12th grade

NAEP: National Assessment of Educational Progress

NAGB: National Assessment Governing Board

NCES: National Center for Education Statistics

NRC: National Research Council

NSF: National Science Foundation

NSLP: National School Lunch Program

NTPS: National Teacher and Principal Survey

OECD: Organisation for Economic Co-operation and Development

PISA: Program for International Student Assessment

SASS: Schools and Staffing Survey

SES: socioeconomic status

STEM: science, technology, engineering, and mathematics

TEL: technology and engineering literacy

TIMSS: Trends in International Mathematics and Science Study

UK: United Kingdom