Lesson 2.4: Alternative Text

When creating digital course documents, it is important to pay attention to the use of images to make sure they meet basic accessibility criteria. Charts, pictures, graphs, and other visual references are frequently used to supplement course material. We will review an often-neglected best practice which is necessary to ensure people with disabilities, poor internet connectivity, or less-powerful computers can enjoy visual content.

Writing Alternative Text

The simple guiding rule for image use within course resources is to have a meaningful textual description of the information each image represents. This description is called alternative text. Alternative text should be complete enough to replace the image entirely and convey the same meaning, yet it should be concise. A good rule of thumb is that alternative text should be 180 characters or less.

For more complex images, graphs, and charts, the alternative text should be the name of the image, and a longer, more detailed text description should be provided in addition to the alternative text. This text description should be either (a) positioned clearly near the image it corresponds to, or (b) incorporated into the explanatory text material surrounding the image.

If an image is just for decoration (i.e. “eye candy”), the alternative text should be denoted as decorative.  Microsoft Word 365 has added a “Mark as decorative” checkbox to the Alt Text window.  For other versions of Word it is advised to limit the use of decorative images and to label them as “decorative” in their alternative text.

For decorative images in Google Docs, run the Grackle Docs add-on.  In the window on the right-hand side, find the decorative images.  Click the Locate +TAG button and check “Mark as artifact” in the Tag Images or Graphs pop-up window.  

Watch the following video to learn more about alternative text.

Google Doc: Understanding Alternative Text Video Transcript

When incorporating images into your content, ask the following questions:

  • Do all images include alternative text?
  • Is alternative text available for all charts, tables, diagrams, graphs, and other visual information?
  • Does the alternative text suffice to replace, not simply describe, the image?
  • Are longer alternative text descriptions either positioned near images or incorporated into the relevant text material?

Image use within course documents can be a very valuable resource for instructors to portray information in a clear and concise manner. Alternative text allows the information housed within an image to reach all students.

Additional Resources

To continue, select the Lesson 2.5 button below.