How do I make my online PowerPoint presentation accessible?
Microsoft PowerPoint™ has become a standard format for creating and presenting visuals (e.g., slideshows) for presentations, including those used in educational contexts such as distance learning courses. A variety of approaches are used for delivering PowerPoint content online, each of which has strengths and weaknesses concerning accessibility.
The most basic approach is to provide the original PowerPoint files for students to download. Access to these files requires that users have either the PowerPoint application or the PowerPoint browser plug-in, which shows PowerPoint pages directly in the browser. If all slides contain simple, standard content such as a heading and bulleted list, these are readily accessible to PowerPoint users with disabilities, including those using assistive technologies such as screen readers. However, as content increases in complexity (e.g., graphics, animations, tables and charts) accessibility decreases.
Users who don't have the PowerPoint application might be able to access native PowerPoint files within the browser plug-in, which is installed automatically in recent versions of Internet Explorer™, but users of other browsers must locate, download, and install the plug-in, providing one exists for their browser. The plug-in provides only visual access to the slideshow and is not accessible to screen reader users.
Another common approach is to use PowerPoint's built-in web publishing feature, which creates a website with multiple frames: One frame contains links to each slide, while another frame contains the slides. Additional frames provide navigational controls. Each slide is presented as text in an HTML file, formatted with extensive proprietary markup that screen readers sometimes fail to render correctly. Screen reader users also face considerable challenges navigating the frames interface, though it's possible with skill and patience.
WebAIM has developed a tutorial covering various alternative methods for delivering PowerPoint content online. In their document PowerPoint Accessibility Techniques, they describe the problems associated with the methods described above and discuss and provide examples of the following alternative techniques:
- Use the Virtual 508.com Accessible Web Publishing Wizard for Microsoft Office. This free tool, developed at the University of Illinois, attempts to convert PowerPoint, Excel, and Word documents into valid and accessible HTML.
- Make your own HTML, using the outline from your PowerPoint file.
- Don't use PowerPoint. Instead, use HTML-native slide generation programs, such as the World Wide Web Consortium's Slidemaker or HTML Slidy, or Philip Greenspun's WimpyPoint.
- Create your own HTML-based slides from scratch using your favorite HTML editor.
Exporting to PDF may also be an option. Doing so using the Adobe PDFMaker plug-in for Microsoft Office by default creates a tagged PDF file, which is optimized for accessibility, and is readable using recent versions of select assistive technologies. Additional information about PDF accessibility is available in the AccessIT Knowledge Base Article Is PDF Accessible?
Regardless of which of the above techniques is used, additional steps are required to assure accessibility, including adding alternate text to images prior to exporting. A relatively recent option, and one of the most promising, is a software product called LecShare, which walks authors through the process of making their PowerPoint accessible, prompting for missing alternate text, as well as for information that can be used to make tables and charts accessible. LecShare then exports to a set of lean, standards-compliant XHTML files with fully accessible markup.