Brightspace, our Learning Management System (LMS), is designed with accessibility in mind. However, it is the responsibility of the instructor and/or course designer to ensure their course content is formatted using best practices for accessibility; including the use of good heading structure, text formatting, contrast and color, descriptive links, alternative text, tables, lists, etc.
I am writing a series of accessibility related blog posts that will provide suggestions on how you can make small changes when creating course content to make it accessible. This is the fourth tip in my series of accessibility related blog posts and it focuses on alternative text (alt text).
Computers can read text on a screen but images, graphs, and charts are meaningless to visually impaired users. Alt text is an alternate method for supplying information about images to users who are visually impaired.
Alt text is important for screen reader users because a screen reader cannot describe an image. Since screen reader software cannot interpret images, it relies on alt text to communicate image information to the user. When an image does not have alt text the only information the screen reader can relay is that there is an image on the page and provide the file name for the image.
Write Helpful Alt Text to Describe Images
Alt text should describe an image so it makes sense in context. If a picture is worth a thousand words, then a short alt text description may be a poor substitute. While a concise alt text description is important, the alt text should be less than 150 characters. You want to think about what is the most important information you are trying to get across with the image and stay within 125-150 characters, or 1–2 sentences. While there is no strict technical limit, brevity is considered best practice, with some guidelines recommending ~125 characters, as it is often a good length for clarity and speed. If the image requires a lengthy description, you should describe the image in the content of the page.
There are several ways to handle complex images (e.g. charts, data, statistics, etc.) where a short description is not possible. The best solution is to include a thorough description of the complex image in the content of the page, immediately before or after the image. If you don't want to add more content to your page, another preferred alternative would be to create another web page with just a description of the complex image and link to it near the image. Additionally, text descriptions of graphs and charts can help all students understand difficult concepts.
How alt text is written will vary depending on the type of image. Most screen reader software announces the presence of an image by appending a word such as "graphic" to the alt text, so using words such as "image" "graphic" and "photo" are unnecessary in the alt text, unless it helps to convey further meaning important for a user to know.
Consider this example which uses “Guide Dog and Man” as the alt text:

The alt text “Guide Dog and Man” is not effective if the intent is to show the dynamic action of guiding in the picture. In this situation a better alt text description is “A man walks confidently with his guide dog in a park, showcasing their dynamic partnership in navigating the path.” There is no need to include "image of," "picture of," or "photo of" in the alt text in this example because the screen reader will announce the presence of the image.
Additionally, images that contain text (as in a logo) should generally be coded to just include that text as the alt text.
Many images are used only for visual interest, they aren't meant to convey any meaning or important information. In this case, it is best to use what is called NULL alt text or empty alt text. This is done by entering two quotes ("") with no spaces in between in the alt text box.
There are a number of free AI image alt text generators available. Here are links to two free AI image alt text generators that I use:
Once you have your alt text, how can you add it to images? Listed below are instructions for adding alt text in MS Word documents, PowerPoint presentations, Google Docs and Slides, as well as in Brightspace.
Add Alt Text to image in MS Word and PowerPoint:
- PC users: right-click on an image
Mac users: press control key and click on the image
- Select Edit Alt Text

- In the Alt Text pane, type 1-2 sentences in the text box to describe the object and its context or click on Generate a description for me. If the image is purely decorative, check the Mark as decorative box and leave the alt text box blank.

Add Alt Text to image in Google Docs and Slides:
- PC users: right-click on an image
Mac users: press control key and click on the image
- Select Alt text

- Enter description

Add Alt Text to image in Brightspace Editor:
When adding an image you will be prompted to provide alternative text. Enter the ALT Text in the Alternative Text field. When an image is decorative, simply check the image is decorative box.
Additional Resources
Here's a list of resources where you can find more information about alternative text:
You will remove significant barriers for the visually impaired if you take these suggestions into consideration when creating course content. An added bonus is that there will be students without disabilities, as well as those who have chosen not to disclose their disability to you, who will find your use of these tips helpful as well.
Image credits:
"Screen Reader" by Widad Sirkhotte is licensed under CC BY-SA 2.0
Photo by Gustavo Fring from Pexels