STEM: Digitally Accessible Course Content

STEM (Science, Technology, Engineering, and Mathematics) disciplines often involve content that presents unique challenges for digital accessibility, including complex images, equations, graphs, and interactive elements. This page offers best practices and curated resources to support departments in making their materials more accessible and compliant.

Accessible Complex Images

Complex images in STEM, such as charts, diagrams, and graphs, play a critical role in conveying information that can't always be communicated in short sentences or phrases characteristic of alt-text in images. If you are unsure of what type of image to include alt-text on, the World Wide Web Consortium (W3C) has created an alt-text Decision Tree .

The National Center for Accessible Media (NCAM) has developed guidelines for describing complex images, plus a variety of examples. These are available in their Effective Practices for Describing STEM Images.

Describing Figures, a guide from the ACM Special Interest Group on Accessible Computing (SIGACCESS).

The A11Y Collective has provided The Ultimate Checklist for Accessible Data Visualisations discussing essential design principles to create accessible charts and figures.

The WebAIM Screen Reader User Survey Results provides a good example of data presented in a variety of ways (graphs, tables, and text descriptions). This is an example of universal design, communicating ideas using multiple means since humans are highly diverse in how they process complex information.

  • Providing Descriptive Alt-Text for Complex Images
    • Include concise descriptions of the image's purpose.
    • For detailed images, provide a summary of key information.
  • Use Long Descriptions
    • When alt-text is insufficient, provide detailed description in text below the image or in a linked document.  There are situations where the composition of an image is important and needs to be provided in the long description.
      For example, the sequence of colors used and the relative heights of the columns in a bar chart may be relevant information about the structure of the chart, in addition to the actual values and trends that it depicts.
  • Label Key Elements
    • Ensure all axes, data points, and critical components are labeled clearly.
    • Avoid relying solely on color to differentiate elements. Using patterns or shapes could provide a clearer indicator. For more guidance see Visual Characteristics.
  • Accessible Data Tables

Accessible Math and Scientific Equations

Equation accessibility is important for several audiences including screen reader users, low vision users requiring magnification and users with reading differences who use text to speech. Below are several options that are available to create and support equation accessibility.

MathML

Math ML (Mathematical Markup Language) is a text-based XML markup language designed for math equations. It is an ideal option as it integrates with screen readers, allows equations to be stored as structured text, can be reformatted with CSS and expanded with good resolution for low-vision users, which enables accessible equation navigation.

MathML is especially recommended for:

  • Superscripts and subscripts
  • Complex fractions
  • Square roots
  • Matrix Expressions
  • Integrals
  • Summations

There are certain situations where MathML may not be needed and plain text may be better:

  • Numbers (e.g. 12,234 or 12.56)
  • Numbers with currency symbols (e.g $12.99).
  • Just a letter variable (e.g. x).

Note: Some users of JAWS (a popular screen reader) have requested to use MathML only for expressions with particularly complex layouts. Plain text equations are best suited for expresions which are one line and have no superscripts/ subcripts or complex layouts. Use best judgement to determine which format may be best.

LaTeX

LaTeX is a math markup language that may be commonly found in the math and science community, but it is unfortunately not consistently supported by most screenreader technology. 

Despite that, many mathemeticians, including those with disabilities can use raw LaTeX code. It is recommended to use tools like MathJax (a JavaScript display engine for mathematics that work in all browsers and is compatible with most screen readers) to render LaTeX equations into accessible formats for web-based platforms. 

Avoid PDF and Conversion Tools to MathML

A PDF file created from a .tex file is rarely accessible, and as noted on our Accessible PDFs page, remediating a PDF document is often a difficult process. If content is stored in a LaTeX .tex file, or R markdown file, utilites such as Pandoc (a universal document converter) can be used to provide an accessible format like Word or HTML. Canvas Equation Editor and the Word Equation Editor can assist with converting raw LaTeX code to MathML, and vice versa.

MathML and LaTeX Tools and Resources

Equations: Avoid Using Image with Alt-Text

Some earlier guidance on digital accessibility may have suggested using an image of an equation with alt-text as a solution, however that method provides its own challenges and there are better solutions present now. 

Issues with this method include:

  • Images getting fuzzy/ unclear under magnification by low-vision users.
  • Screen reader options for complex equations are better with MathML in which they can choose to read individual parts of the equation (e.g. the numerator of a fraction, etc). 

Provide Text Descriptions and Structured Navigation

Mathematical notation is an essential part of communicating complex ideas in STEM disciplines, but it is important to keep in mind that students who use screen readers or who have cognitive/ learning disabilites may struggle to understand mathematical expressions solely presented as symbols or equations.

Plain-text explanations of equations and their significance alongside the mathematical notation serves as an accessibility enhancement by providing necessary context, logic, and narrative flow behind the symbols and notation. This is especially useful for users of assistive technology as it helps them understand what the equation is communicating when dealing with complex nested expressions. 

It is also recommended to structure equations to allow screen readers to navigate components hierarchically. 
For example, breaking down this LaTeX inline equation $E=mc^2 will give E=mc^2, but E=mc^2 when not formated correctly, for example as plain text or when using raw LaTeX could present through screenreader as "E equals m c two" missing out on communicating the exponent. 

By using tools and formats that support semantic math (MathML, Canvas Equation Editor, etc) you're ensuring that students using screen readers can understand the structure and formatting of the equation, not just the visual appearance. 

Inclusive Document and Presentation Practices

 For course materials such as lecture slides and handouts shared digitally:

  • Use Structured Headings
    • Organize content with clear headings and subheadings to facilitate navigations. For more guidance see Headings.
  • Ensure your Links are Descriptive
    • Use meaningful link text (e.g., "View graph of molecular structure" instead of "Click here") For more guidance see Links.
  • Best Practice is to Avoid PDF's
    • If you must use PDF's use OCR (Optical Character Recognition) for scanned documents and tag PDFs for screen reader compatibility. For more guidance see PDF's.

Captioning and Transcripts for Multimedia

Video and audio content can help make course curricula more engaging. However, they can also erect barriers unless delivered with accessibility in mind. Videos should be produced and delivered in ways that ensure that all members of the audience can access their content.

  • Captions
    • Provide synchronized captions for all videos, including descriptions of mathematical or visual content. For more guidance see Captions.
  • Audio Descriptions
    • Provide a spoken narration of essential visual content in multimedia, ensuring accessibility for blind/ low-vision individuals. For more guidance see Audio Description.
  • Transcripts
    • Include detailed transcripts that describe visual and auditory elements in addition to spoken content. For more guidance see Transcripts.