5 Unit: 5: Equations
In this unit, we review how to add accessible formulas to content. After working on this unit, you are expected to be able to:
- Use the correct special characters to write simple math equations.
- Describe what MathJax is and how it works.
- Use images of equations and alternative text to create accessible math equations.
Equations and formulas can be found in all sorts of disciplines and in varying levels of complexity. Perhaps your subject uses equations or formulas rarely or maybe it is a core part of the curriculum. Either way, there are a number of considerations to keep in mind when using any type of equation or formula, no matter how basic.
These considerations include:
- How to use special characters and symbols so they will be read properly by screen readers
- Using MathJax to render equations written in LaTeX or MathML
- Providing alternative text to images of equations
Who are you doing this for?
This work supports students who:
- Are blind, like Jacob
- Have a learning disability that affects their ability to interpret equations
A common mistake is for authors to use incorrect symbols to create simple equations. This is generally the case in educational resources that are not math-focused or math-heavy, but still include basic equations or need to convey things like negative temperatures or the charge of an ion in chemistry.
Here are a number of symbols and characters that might be used to signify multiplication:
x or × or ⋅
However, a screen reader would only read the middle symbol as “times.” The first would be read as the letter “x” and the last would be read as a dot.
Here is another example. This is a list of characters that might be used for subtraction:
– or − or —
The first and last symbols are a hyphen and an em-dash, and as such, screen readers don’t announce their presence unless settings are changed. Only the middle symbol is something a computer would read as a “minus” sign.
Here are two more examples. The first shows a division sign and a forward slash.
÷ or /
The last example shows two fractions. A screen reader would read the first fraction as “two-thirds” or “two over three.” It would read the second fraction as “2, 3.”
⅔ or 2/3
Because of how easily these symbols and special characters can be misinterpr
eted by screen readers, it is good practice to check to make sure the symbol you insert will be read in the manner you expect it to be. You can often check this by hovering over or clicking the character to seewhat it is called.
Image description: A screenshot of a list of recently used symbols. The minus sign symbol is highlighted to show it has been clicked. The Unicode name for the symbol is listed underneath.
If the authoring platform you are using does not provide a collection of symbols to insert, you can also use a search engine to find the correct symbol and copy and paste that symbol into your document.
When dealing with more complex math equations and formulas, using symbols is no longer enough. One option is to write equations using a mathematical markup language, such as MathML, LaTeX, or AsciiMath, and then use MathJax to render those equations.
MathML is a markup language that can be interpreted by screen readers. With MathML, blind students can have an equation read out to them. However, MathML is a very hard language to learn and not all browsers can display it. This is where MathJax comes in.
MathJax is a display engine that will ensure the equations written in MathML will display consistently and properly across browsers.
MathJax will also translate equations written in LaTeX or AsciiMath into MathML so they are accessible to students using screen readers. As long as the markup prioritizes the meaning of equations over the display, then screen readers will be able to accurately interpret the equations.
MathJax has a number of other accessibility extensions. For example, students can enlarge equations without lowering the resolution, students can have equations read aloud to them, and students can collapse parts of large equations to make it easier to work through them step by step (MathJax, n.d.).
For more details, refer to https://accessibility.psu.edu/math/mathml/
A final option to create accessible equations is to use images with alternative text descriptions. You can create the image using an equation editor, such as one available in Microsoft Word, and then export the equation as an image and add alternative text. The alternative text can be written in MathSpeak for students who have learned that system. MathSpeak is a set of grammar rules for translating equations into English (University of Washington, 2019).
| Example: Image of an equation with alternative text
|
Alternative text: m equals begin fraction m sub 0 over begin square root 1 minus begin fraction v sup 2 over c sup 2 end fraction end square root end fraction
In Unit 5, we explored various strategies for how to make formulas and equations accessible to students using screen readers. We discussed how to properly use special characters and symbols, how MathJax works and the option to use a combination of images and alternative text descriptions written in MathSpeak. The method you select will depend on your subject, the platform you use, and your knowledge of mathematical markup languages.
1. True or false? All of these symbols will be read by a screen reader as “minus” when used in the context of a math equation: -, −, —
a) True
b) False
2. Which of the following is a tool that renders mathematical markup languages into accessible equations?
a) LaTeX
b) MathJax
c) MathSpeak
d) MathML
- Which of the following is a mathematical markup language that can be interpreted by screen readers?
a) LaTeX
b) MathJax
c) MathSpeak
d) MathML
- Which of the following is a set of grammar rules used for translating equations into English?
a) LaTeX
b) MathJax
c) MathSpeak
d) MathML
- True or false? Images of equations with alternative text written in MathSpeak are accessible to blind students.
a) True
b) False
