Overview
For many instructors, visuals are central to how ideas are conveyed in a course, but translating visuals into words can feel overwhelming. If you’ve wondered what needs description, how detailed to be, or how to approach image-heavy materials, you’re not alone. The suggestions below are meant to be a toolkit; our hope is that you’ll find a few ideas that fit your specific context.
What Is Alt Text? (And What It’s Not)
Alternative text is a brief description that the content creator embeds behind the image. Alt text is not usually visible on the page, but it plays an important role behind the scenes; it appears if an image fails to load, for example, due to a missing file or slow connection, so that the image’s information remains available. Also, students with disabilities, who use text-to-speech software to pace their reading and those who use screen readers, rely on alt text to describe graphics as they study. More fundamentally, providing text alternatives for non-text content is a baseline requirement for equitable access to information.
Alt text should convey the meaning or function of the image within its instructional context, not provide an exhaustive description of every visual detail. The aim is to communicate the concept or information the image is meant to convey so that all students can engage with the same content, regardless of how they’re accessing the content.
Note that if you have a student who requires comprehensive, highly detailed descriptions of every visual, they will receive a formal Letter of Accommodation from the Disabled Students' Program (DSP). In those situations, DSP will provide specialized support, such as Braille materials or extended descriptive services.
The First Step: Is the Image Decorative?
Before you worry about writing a description, ask: Does this visual actually need one? Not every image does.
To help take the guesswork out of this, the Web Accessibility Initiative offers a practical decision tree. Here is a quick checklist you can use when adding an image to your course:
- Is it purely for aesthetic flair? (e.g., a generic stock photo of a campus building at the top of a syllabus). If yes, simply right-click the image, select Alt Text, and check “Mark as decorative.”
- Is it an image of text that is already typed out in the paragraphs nearby? If the information is redundant to the surrounding text, mark the image as decorative.
- Does it contribute new meaning to the lesson? If it's a simple graphic, write a brief description. If it's a complex graph, provide a short alt text and include the actual data elsewhere on the page.
Tips for Better Alt Text
If the image does have instructional value, here are a few ideas for writing effective descriptions, drawn from our own campus resources:
- Keep it concise: Screen readers cannot easily "pause" or "rewind" alt text, so brevity is really helpful. Aim for one to two short sentences.
- Context is everything: Describe the visual based on why it is in your lesson. A photo of the Golden Gate Bridge in an engineering course might require a very different description than the exact same photo in a photography course.
- Alt text in exams: To provide alt text without giving away the answer, a helpful rule of thumb is to describe the data or components, but not the conclusion. For instance, instead of "Bar chart showing emissions doubled by 2020," you might try, "Bar chart plotting global carbon emissions from 2000 to 2020."
A Quick Note on STEM and Complex Visuals
We frequently hear from instructors in STEM and highly visual fields that standard alt text is challenging to create for their materials. RTL guidance on accessible STEM slides recommends thinking in layers. Use alt text to communicate the overall structure, trend, or key takeaway, and then provide additional detail in the caption, surrounding text or notes when precision matters.
For equations, screenshots of mathematical formulas are not readable by screen readers. We recommend ensuring that equations are available in machine-readable formats such as LaTeX or MathML rather than relying solely on images. When you use the Canvas Equation Editor, the system converts your LaTeX into MathML for screen reader navigation, renders it as an SVG for crisp visual display, and retains the LaTeX code as alt text–creating a comprehensive, accessible ecosystem for every student.
When There Are Hundreds of Images
For instructors teaching heavily visual courses, updating slide decks with hundreds of images is a massive undertaking. Some instructors are using AI tools like Gemini to generate first drafts of alt text in bulk.
Important: To protect sensitive data, always sign in to your bConnected suite with your CalNet account to use Gemini. This ensures your content is not used to train external models.
For Single Images, capture the image, paste it into Gemini, and type: "Provide concise alt text for this image." Make sure to verify the output before inserting it into your document.
For a Bulk Slide Deck, save your slides as a PDF, upload it to Gemini, and and use this prompt: "Analyze the attached file and create a table listing every image and stock photo found (do not group them). Create a table with these columns: Page Number, Visual Reference, Alt Text (Provide a concise sentence describing the image's core meaning or data trend)."
While this workflow can save enormous amounts of time, it is a starting point, not a perfect solution. AI may occasionally skip images or misinterpret context, so you will still need to review the generated text to ensure it matches your instructional intent.
Final Thoughts
Sometimes writing alt text clarifies our own teaching: What is the point of this image? What do I want students to see? Keep in mind that alt text is not about describing everything. It’s about providing equivalent access to meaning.
If you’re interested in hearing more about the broader Title II updates, you can also listen to our latest Finding Space podcast episode, where Anne Marie Richard, Assistant Vice Provost for Undergraduate Education and Chief Academic Technology Officer, discusses what the new requirements mean for higher education and shares five practical steps instructors can begin taking now. You can also contact us to schedule a representative from RTL to meet with your department. In our outreach sessions, we will review WCAG 2.1 AA requirements, address field-specific areas of interest, provide guidance on prioritizing accessibility work, and facilitate time for questions and answers. Schedule a time using the RTL accessibility intake form.