Imagine you’re a student in an introductory biology course. On an exam, your professor asks: "What is a byproduct of photosynthesis as exhibited by Figure 1.1 below?" Could you answer the question?
To be accessible, all graphics must have alt text or a transcription that describes them. Screen readers and other machines (such as search engines) can't read images and rely on text alternatives and transcriptions. Supplying concise and equivalent alt text ensures equitable course content for all students and all types of devices.
Providing this information in a chart rather than in alt text will assist students who use screen readers with navigating the information in the graph/chart. While alt text is helpful, there is no way for the student who is using a screen reader to navigate a lengthy paragraph. In a chart or list format, the student can navigate easily with a screen reader. Keep in mind that alt text doesn’t have to exist in the same format the original image does. If you’re unsure of where to start, here are some best practices.
Post Authors:
Christy Jersin Woods an Instructional Designer Associate for the School of Life Sciences at ASU. She leverages technology and inclusive teaching pedagogy to assist faculty in curriculum and design of their courses. Currently, Christy is earning her Master’s in Educational Leadership and Graduate Certificate in Educational Technology from Northern Arizona University, both of which she will complete this year. She has several years of experience teaching and in curriculum design in higher education and continues to stay up to date in literature and best practices.
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| Figure 1.1 |
Now imagine you are a student who has a visual impairment and you were asked the same question. Could you provide the answer then? Chances are you may not be able to answer the question based on Figure 1.1 alone. What seems like a well-written question, is actually only accessible to students who are sighted or otherwise have functional vision. For students with visual impairments, assessment questions based solely on scientific images or graphs may create a barrier in the learning process. Being web inclusive means that course content and associated materials are equitably available to all students regardless of their abilities, or type of technological device that they are using. Instead of relying only on scientific images and graphs to showcase data, you can improve access to course materials by also providing Alternative Text (alt text). The purpose of alt text is to provide a text equivalent of the image, so people who are unable to see the image have access to the message it’s intended to convey. Students using alt text regularly may include those with low vision or students with cognitive impairments that work more efficiently with text than images.
To be accessible, all graphics must have alt text or a transcription that describes them. Screen readers and other machines (such as search engines) can't read images and rely on text alternatives and transcriptions. Supplying concise and equivalent alt text ensures equitable course content for all students and all types of devices.
An Example of Alt Text for Scientific Data
Here’s an example of alt text to describe Figure 1.1 (as seen above):
A plant at the center of the cycle of photosynthesis. It takes water in through the roots, carbon dioxide and sunlight through its leaves. The leaves release oxygen back into the air as part of the cycle.
In this example, the alt text details the scientific data thoroughly, and may inadvertently give away the answer to the original question, “What is a byproduct of photosynthesis as exhibited by the diagram below?” This is a concern when using alt text for scientific graphs and images. Professors are wary of giving away the answer, but also want to make sure their course materials are accessible and equitable for all students. Writing alt text descriptions for graphs can be particularly challenging without giving away the answers.
So what can you do?
Write better questions.
Write questions that do not rely solely on visual stimuli. For example, instead of using the initial question, instead, you might ask, “Which aspect of the photosynthesis cycle serves as the source of energy to fuel a light-dependent chemical reaction inside of the leaves?” Or you may ask, “Which aspects of the photosynthesis cycle serve as sources of energy for light-independent reactions inside the leaves?” These questions ask the student about their content knowledge of photosynthesis rather than their ability to visually see an image.
Reformat complex text.
If the question you want to ask is based on the student’s ability to read and interpret complex text, such as a scientific graph or chart, and cannot be limited to a succinct alt text, you may consider reformatting the text into an accessible table or list instead. For example, if you ask students to interpret the bar chart below, you may also provide the following alt text and accessible table.
Alt text: The figure is a bar chart which illustrates the frequency of number of mistakes while driving. On the horizontal axis or X axis, the number of mistakes while driving is given and on Vertical axis or Y axis, frequency is distributed. The data are summarized in the following table. All data are approximate.
Alt text: The figure is a bar chart which illustrates the frequency of number of mistakes while driving. On the horizontal axis or X axis, the number of mistakes while driving is given and on Vertical axis or Y axis, frequency is distributed. The data are summarized in the following table. All data are approximate.
Accessible table:
Providing this information in a chart rather than in alt text will assist students who use screen readers with navigating the information in the graph/chart. While alt text is helpful, there is no way for the student who is using a screen reader to navigate a lengthy paragraph. In a chart or list format, the student can navigate easily with a screen reader. Keep in mind that alt text doesn’t have to exist in the same format the original image does. If you’re unsure of where to start, here are some best practices.
Alt Text Best Practices for Scientific Images and Graphs:
- Be brief and succinct, while providing enough information for students to successfully complete the assessment.
- Omit Titles and Labels in the Alt Text description.
- Omit unnecessary information (Ex: if the mention of color within a graph or image is not pertinent to successfully completing the assessment, omit it).
- Before describing a graph or image, read the associated assessment questions to determine which information is critical.
- There might be some details of the image that are not relevant to answer the questions, therefore each Alt Text must be tailored to fit in the context of the question.
- Consider prerequisite knowledge that students are expected to know. This will help structure how much detail is necessary in the Alt Text.
Get help with web accessibility and alt text:
There are many resources available to those who want to learn more about making their teaching accessible. The important thing to remember about accessibility and alt text is that you’re not alone. ASU provides many resources to help you ensure your content and your assessments are accessible.- Connect with ASU Accessibility on the #accessibility Slack channel at asu-community.slack.com
- Subscribe to the ITACCESS mailing list
- Book an appointment at the Access Clinic at ASU, held online every Wednesday from 1-5 p.m.
- Connect with Student Accessibility and Inclusive Learning Services (SAILS) at ASU to help provide alt text for your scientific images and graphics.
Tiffany Lewis is an ELS PhD candidate in the School of Life Sciences at Arizona State University. Her research focuses on how we can work with communities to find collaborative solutions to pollution. She is also committed to teaching, learning, and continuing to improve educational environments, particularly online.
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