Glossary – National Center on Accessible Digital Educational Materials & Instruction

Accessibility Overlay: A tool that attempts to improve the accessibility of a website by modifying the presentation of the content to users in real-time, such as by changing the font or color contrast. Overlays are typically third-party tools and can interfere with assistive technologies like screen readers. The Overlay Fact Sheet provides detailed information about accessibility overlays and cautions to consider.
Accessible: A widely accepted definition of “accessible” comes from the U.S. Department of Justice and the U.S. Department of Education: Accessible means “an individual with a disability can access the same information, engage in the same interactions, and otherwise participate in or benefit from the same services, programs, and activities as individuals without disabilities, in a manner that provides substantially equivalent timeliness, privacy, independence, and ease of use.” An original version of this statement appeared in a 2010 joint Dear Colleague Letter to university presidents regarding the adoption of non-accessible technology. References to student privacy and independence were added in the 2024 ADA Title II Final Rule.
Accessible Digital Educational Materials: Digital materials intentionally produced to be accessible from the beginning. Digital textbooks, videos, apps, websites, and even learning management systems can be accessible. Essentially, any digital material provided by state and local educational agencies (SEA and LEAs) must meet minimum accessibility standards under Title II of the Americans with Disabilities Act (ADA) (U.S. Department of Justice, 2024). The Web Content Accessibility Guidelines (WCAG) Version 2.1, Level AA is the minimum technical standard required by ADA Title II. States and school districts are covered entities under ADA Title II and are therefore required to ensure digital educational materials provided by schools meet WCAG 2.1 AA.
Accessible Educational Materials (AEM): Defined by the Office of Special Education Programs at the U.S. Department of Education, “accessible educational materials (AEM)” are “print- and technology-based educational materials, including printed and electronic textbooks and related core materials that are required by state and local educational agencies (SEA and LEAs) for use by all students, produced or rendered in accessible media, written and published primarily for use in early learning programs, elementary, or secondary schools to support teaching and learning.” AEM can be digitally accessible from the beginning, such as accessible digital educational materials, or rendered in accessible formats.
Accessible Format: Under U.S. copyright law, an “accessible format” is “an alternative manner or form that gives an eligible person access to the work when the copy or phonorecord in the accessible format is used exclusively by the eligible person to permit him or her to have access as feasibly and comfortably as a person without such disability.” In other words, an accessible format is an alternative presentation of information that provides access to otherwise inaccessible materials for individuals with disabilities. While a list of specific examples doesn’t exist, common types of accessible formats for text-based materials include braille, large print, audio, digital text, and tactile graphics. Videos can be made accessible with closed captioning, audio description, and synchronized American Sign Language (ASL). Audio can be made accessible with text transcripts.
Accessible Instructional Materials (AIM) Consortium, 2007-2008: The AIM Consortium was a project funded by the Office of Special Education Programs at the U.S. Department of Education from 2007-2008. Led by CAST, teams from fifteen states received technical assistance in the implementation of the National Instructional Materials Accessibility Standard (NIMAS) and National Instructional Materials Access Center (NIMAC). The states included Delaware, Georgia, Iowa, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Missouri, New York, Pennsylvania, Utah, Vermont, Wisconsin, and Wyoming. These states benefited from constructive collaborations and were the first to develop and use Quality Indicators related to the provision of accessible materials.
Accessible Media Producer (AMP): Agencies, organizations, or other services that convert materials, including textbooks and related curriculum materials, to one or more student-ready accessible formats.
Accommodation: An allowed adjustment or alteration to a curriculum that provides access for a student with a disability. An accommodation does not change what a student is expected to master; rather, it provides access. The objectives of the curriculum remain intact.
Americans with Disabilities Act (ADA): An anti-discrimination law that protects people with disabilities in many areas of public life, including education. It is administered by the U.S. Department of Justice (DOJ). Title II of the ADA applies to state and local government entities, including state and local educational agencies (SEA and LEAs). In 2024, DOJ published a final rule under Title II, specifying accessibility requirements for web content and mobile apps.
Assistive Technology (AT): An AT device is defined under Individuals with Disabilities Education Act (IDEA) as “any item, piece of equipment, or product system, that is used to increase, maintain, or improve the functional capabilities of a child and specifically excludes a medical device that is surgically implanted or the replacement of such device” (e.g., a cochlear implant). AT devices are often viewed on a continuum of low-tech (e.g., a pencil grip), mid-tech (audio book), or high-tech (e.g., dynamic communication device).
Audio: An accessible format that uses human-recorded or synthetic voice narration to present information. Audio can be stored and transmitted through both analog and digital means.
Audio Described Video (also commonly referred to as Audio Description): The verbal explanation of essential visual elements in a video or other multimedia resource, providing access to the visual content when the audio component alone is insufficient for perceiving on-screen actions.
Authorized User (AU): An agent of a state educational agency who has access to the NIMAC database in order to download or to assign NIMAS fileset(s) for conversion to accessible formats in accordance with established agreements with the NIMAC. An AU can be a nonprofit organization or a governmental agency. Examples of AUs include accessible media producers (AMPs), such as Bookshare and State Instructional Resource Centers (IRCs).
Braille: Braille code is a tactile system of raised dots that enables students who are blind or have low vision to read through touch. Braille consists of patterns of raised dots arranged in cells of up to six dots in a 3×2 configuration. Each cell represents letters of the alphabet, punctuation, numbers, and whole words. In the case of a child who is blind or visually impaired, provide for instruction in Braille and the use of Braille unless the IEP Team determines, after an evaluation of the child’s reading and writing skills, needs, and appropriate reading and writing media (including an evaluation of the child’s future needs for instruction in Braille or the use of Braille), that instruction in Braille or the use of Braille is not appropriate for the child; Sec. 300.324 (a) (2) (iii).
Captions: Synchronized text representations of audio content in videos or multimedia productions that include spoken words and other important audio information. Closed captions are captions that can be turned on and off by the user while open captions are always visible and cannot be turned off.
Copyright: Legal protection for intellectual property that controls reproduction, distribution, and adaptation of original works, preventing their use or duplication without the owner’s permission.
Digital Text: An accessible file format that contains both text and images. Examples of file types include accessible EPUB, HTML, MathML, and tagged PDF.
Individualized Education Program (IEP): A legal document for a student with a disability that is developed, reviewed, and revised in accordance with Individuals with Disabilities Education Act (IDEA) regulations. An IEP has specific requirements, such as mandatory team membership, an annual review, annual measurable student goals, participation in the state assessment, and participation in the general curriculum.
Individuals with Disabilities Education Act (IDEA): The U.S. special education law that ensures services for infants, toddlers, children, and youth with disabilities through age 21. IDEA governs services provided by states and public agencies.
Large Print: An accessible format provided in a hard copy document containing a font size of 18 points or larger. Additional formatting considerations pertain to styles used for font face and punctuation, format options, use of color, paper selection, and document size.
Local Educational Agency (LEA): A term for public education agencies that are locally situated, such as education service agencies or school districts.
National Accessible Educational Materials (AEM) Center, 2014-2019: The National AEM Center was a project funded by the Office of Special Education Programs at the U.S. Department of Education from 2014‒2019. Led by CAST, teams from eight states developed partnerships and received technical assistance in the use of the Quality Indicators. The states included Alaska, Florida, Indiana, Iowa, Maryland, Minnesota, Ohio, and Texas.
National Accessible Instructional Materials (AIM) Center, 2009-2014: The National AIM Center was a project funded by the Office of Special Education Programs at the U.S. Department of Education from 2009–2014. Led by CAST, teams from ten states developed partnerships and received technical assistance in the use of the Quality Indicators. The states included Connecticut, Idaho, Maryland, Nevada, New Hampshire, New Mexico, Ohio, Oklahoma, Oregon, and West Virginia.
National Center on Accessible Educational Materials for Learning (AEM Center 2.0), 2019-2024: The National AEM Center 2.0 was a project funded by the Office of Special Education Programs at the U.S. Department of Education from 2019–2024. Led by CAST, teams from seven states developed partnerships and received technical assistance in the use of the Quality Indicators. The states included Georgia, Missouri, New Hampshire, North Carolina, Oklahoma, Oregon, and West Virginia.
National Instructional Materials Access Center (NIMAC): An online repository operated by the American Printing House for the Blind (APH) that receives National Instructional Materials Accessibility Standard (NIMAS) source files in accordance with instructional material contract language set by states and school districts. Once a file is received, the NIMAC validates, reviews, and catalogs it in its repository.
National Instructional Materials Accessibility Standard (NIMAS): A technical standard used by publishers to produce electronic source files of textbooks and related instructional materials that can be converted into different types of formats, including braille, large print, and accessible digital text. NIMAS files are not in a student-ready format. Rather, they’re in a code programmed to speed the process of conversion to accessible formats. NIMAS source files are made available via a secure, online system to registered Authorized Users and Accessible Media Producers for use in the production of accessible formats.
Portable Document Format (PDF): A file format developed by Adobe that maintains a document’s formatting and layout regardless of the software or hardware used to view it, making it easy to share and print. A popular file format, PDFs are frequently non-accessible for students with disabilities. PDFs are accessible when creators follow common practices for accessible documents.
Procurement: The process used by state and local educational agencies (SEA and LEAs) to source or purchase educational materials. Procurement is also the process through which SEAs and LEAs require publishers to submit NIMAS files to the NIMAC.
Request for Information (RFI)/Request for Proposal (RFP): An open request for bids to fulfill a state or local educational agency’s need for new educational materials.
Section 121/Chafee Amendment of the Copyright Act: Section 121 allows certain organizations (e.g., schools, libraries, and nonprofits that serve people with print disabilities) to make accessible versions of copyrighted books and other published works without needing permission from the copyright holder. It’s also known as the Chafee Amendment in recognition of Senator John H. Chafee, who introduced the amendment to Congress in 1996.
State Educational Agency (SEA): A term for a state department of education.
Tactile Graphics: Graphics that convey non-textual information through touch to people who are blind or have low vision. These may include tactile representations of pictures, maps, graphs, diagrams and other images. Students who are blind or visually impaired touch these raised lines and surfaces to access the same information as students who are sighted.
Text Transcripts of Audio: A text version of the speech and non-speech audio information needed to understand the content in an audio-only file.
Web Content Accessibility Guidelines (WCAG): Technical standards developed by the World Wide Web Consortium (W3C) to make websites and other digital materials accessible for individuals with disabilities. The minimum standard required by the Americans with Disabilities Act (ADA) Title II is WCAG version 2.1, Level AA. WCAG defines three levels of conformance: “A” (lowest), “AA” (more comprehensive), and “AAA” (highest and often considered aspirational).