Guideline 6
Provide access to math equations for all users with disabilities.

Current interfaces to equations in educational software pose two sets of problems: first, users who are blind cannot read equations (and users with low vision may have trouble reading them at small sizes), and second, both users with visual impairments and those with physical disabilities have difficulty using equation input and editing interfaces that require use of a mouse.

Checkpoint 6.1
Allow all equations to be enlarged on screen.
Priority 1
A zooming or scaling feature, similar to one common in word processors, will improve access for users with low vision by allowing them to enlarge equations for better viewing. Ensure that characters are smooth and legible at the enlarged size. Users may also wish to print out materials at the enlarged size.

Checkpoint 6.2
Ensure that users with visual impairments can read equations and that users with visual impairments and with physical impairments can write equations.
Priority 1
In order to effectively interact with equations, users need to read, write and edit equations. Users must be able to enter all characters needed to create an equation whether they use the keyboard or the mouse. They must know what they have written and where the insertion point is so they can add or delete characters.

Understanding longer or more complex equations requires navigating within the equation to hear different parts separately. Equations provided in educational content that cannot be changed by the reader are referred to here as static equations. Equations that can be edited or written by the user are referred to as dynamic equations.

Currently screen reader software for users with visual impairments cannot accurately read most math equations. Superscripts and subscripts, for example, may be read as a separate line from the rest of the equation's characters, and many special symbols aren't recognized by screen readers. Equations may be rendered as a single graphic and not recognized at all by screen readers.

Software developers may use a range of means to read static equations to users, including direct approaches (providing pre-recorded audio files) and compatible approaches (making equations accessible to screen readers). A direct approach such as pre-recorded files would provide access for blind and low vision students, though not for those who are deaf-blind. The audio must include sufficient information about the structure of the equation to avoid confusing the listener. Unstructured communication is only adequate in cases of very simple mathematics. For example, nested fractions such as (x+2)(3/5) are difficult to convey accurately in speech without a structured way of speaking. See Appendix 4, Guides to Spoken Mathematics, for resources.

Software that allows users to write new material including equations must provide a way to access any user-created text. The best solution is to use a standardized mark-up language that assistive technologies can interpret. The best choice is Math Markup Language, or MathML, defined by the World Wide Web Consortium. Screen readers cannot yet read MathML, but research and development efforts will make this possible soon. Widespread use of MathML by software developers will hasten the creation of solutions for users of assistive technology. See Technique 6.2.1.

A second possible markup language for equation display is LaTeX. Tools do exist for converting LaTeX to Nemeth braille for blind users. These tools are designed to convert entire documents rather than for use with interactive software, but this does permit some access to instructional materials. See Technique 6.2.2.

If these developing technologies fail, it is essential to find an interim solution to make equations accessible to students who are blind. A custom-designed text or text-to-speech solution can provide access to user-created equations without interfacing with assistive technologies. For example, the software developer could use a system of spoken mathematics to write out equations and send equations directly to a text-to-speech program. Care must be taken when using this option to include blind and low vision users in testing to ensure that the amount and timing of the equation voicing meets the users' needs. See Technique 6.2.5 for more information.

Technique 6.2.1
Use MathML to provide access to equations
MathML is the best choice for a mark-up language for expressing math. MathML is a specification of the World Wide Web Consortium (W3C) based on XML. Information on MathML is available from:

The W3C's Math Home Page
www.w3.org/Math

Mathematical Markup Language (MathML™) 1.01 Specification
www.w3.org/TR/REC-MathML

The advantage of MathML is it provides mathematical information in an open, standard format which can be exploited by a wide range of assistive technologies. Research is in progress on the development of specialized browsers or plug-ins capable of providing speech or braille output of MathML content. Information on the MAVIS Project talking MathML browser is available from www.nmsu.edu/~mavis/browser.html and www.nmsu.edu/~mavis/mavistex.html provides additional details.

Math-capable assistive technologies that can interact with mainstream web browsers will likely be developed once MathML becomes a common means of publishing electronic math content. For maximum accessibility, software that includes content written in MathML and HTML should allow users to use a browser which provides the functions they need. If MathML is the protocol used to deliver math content but the product is not HTML-based, the MathML content should be available as part of an operating system accessibility API or in an accessibility mode allowing access by assistive technology.

Once software programmatically exposes the MathML markup used to display math on the screen, assistive technologies will give users interactive control of reading and writing equations. Note that MathML itself is not intended to be human-readable; tools will interpret the markup and create a useful representation in speech or braille.

Technique 6.2.2
Use LaTeX to provide access to equations
LaTeX is a math typesetting language used frequently in academic settings. Tools are currently available that can convert LaTeX files to Nemeth code (math braille). In addition, a "reverse translator," allowing students to enter Nemeth code and produce printed math in LaTeX, is also in development. Teachers can use the MAVIS tools to create brailled math for homework assignments, tests, and handouts without knowing any Nemeth code themselves, and students can write their responses in Nemeth code then produce printed math to submit to their teachers. The current tools convert entire documents rather than allowing for use with interactive software, but they do provide some access by allowing instructional materials to be printed for blind users. If more software used LaTeX to encode math, these tools might be adapted to permit real-time translation of LaTeX to braille for use with interactive software. Information on the MAVIS Project LaTeX to Nemeth converter is available from www.nmsu.edu/~mavis/converter.html and www.nmsu.edu/~mavis/eqip3_10.html provides additional details.

Technique 6.2.3
Use pre-recorded audio to read static equations
A human narrator can pre-record all text including static equations. This audio file allows the user to hear entire equations on command, as well as smaller chunks. Use of the DAISY talking book specification provides a synchronized and controlled audio presentation. (More information on DAISY is available at: www.daisy.org). This technique, unfortunately, does not provide access for all users. For example, deaf-blind students. Consider using audio files as a supplement to one of the other techniques to ensure that your content is universally accessible. See Appendix 4, Guides to Spoken Mathematics, for resources.

Technique 6.2.4
Use concatenated speech strings for simple equations
For simple equations, such as those in elementary level math software, a satisfactory interface can be created by concatenating (stringing together) segments of prerecorded speech. However, the software must provide all commands needed for interacting with the equations. Furthermore, this approach quickly loses effectiveness as equations become more complicated and students need more structural information to interact efficiently with the content.

For example, in the accessible prototype "How the West Was One + Three x Four," created by the CD-ROM Access Project, users can create simple four-function equations. Each character is voiced as it is entered and each character deleted is voiced with the message "deleted." The whole equation can be read back on command. Two digit numbers are read as single digits when entered but as complete numbers when read back. This prototype can be downloaded from the West Prototype section.

Technique 6.2.5
Create equation scripts using guidelines for spoken mathematics
Until MathML tools are better developed, and if other techniques are not possible, software must deliver equations in an alternative form through carefully scripted text. Software can spell out equations on the screen in words, for example 2 x squared plus the fraction 3 over 4," which can then be read by an assistive technology.

Another interim solution is to send equation information directly to a text-to-speech engine. To use this technique, the software must provide a mode where the entire text of the equation is read and commands for reading specific sections of the equation. The software must also allow the user to move through the text in shorter chunks, such as parts of equations. Mechanisms for internal equation navigation may be required to allow the user to read specific elements and determine their position and relationship to other elements within the equation. See Appendix 4, Guides to Spoken Mathematics, for resources.