Editing and creating accessible digital slides is a basic digital competence for any teacher who wishes to participate in the current inclusive education system. To achieve an accessible presentation for all people, we should apply the Universal Design for Learning (UDL) by CAST principles that, in turn, are based on the Guidelines for the Creation of Web Content by W3C-WAI (WCAG), which are today an ISO international standard (ISO/IEC 40500:2012) by ISO.
- Choose friendly fonts
Choose a font that is friendly to people with dyslexia, such as Arial and Comic Sans, as letters can appear less crowded. Alternatives include Verdana, Tahoma, Century Gothic, Trebuchet, Calibri, Open Sans. In any case, fonts from the roman family or with “Serif” should never be used in a presentation.
- Text sizes
- The recommended minimum size is 22 pt. In any case, a font size smaller than 14 points should never be used in a presentation.
- The template adjusts the font size as content is added. Therefore, we must make sure, if we add a lot of content (which is not recommended), that it never appears in a size smaller than 14 pt.
- Spacing between paragraphs
If you want to increase the space between paragraphs, remember:
- Avoid blank lines in tables if possible as they may confuse screen reader users as to whether the table ends there or continues beyond the blank line.
- If we want to achieve a greater spacing between paragraphs, we must click on the button "line spacing" > "line spacing options" and the "Paragraph" dialog will appear. In this, we can modify the spacing before and after the paragraphs that we have selected.
- We can use the outline view to check if we have left any blank lines and, if necessary, delete them.
- Mark language changes
If we enter text in a language other than the main language of the presentation, we must mark the language change. To do this, select the text, click on "Review" > "Language" and choose the language.
- Use meaningful text in hyperlinks
Text associated with hyperlinks must provide a clear description of the link destination and be presented in a readable format. The hyperlink text must not provide just the URL address or just the name of the file being accessed, if that is the case.
To make a hyperlink more accessible, you must select the link and click on Insert > Link. In the Text to display field, type a phrase that briefly describes the destination of the link.
- Avoid text boxes
Always avoid adding text boxes and instead use the bookmarks found in the slide master view, creating a new layout style for that purpose.
- Pay attention to colour contrast
- The Foreground text needs to have sufficient contrast with the background colours. Some people cannot read the text if there is not sufficient contrast between the text and the background.
- For others, bright colours (high luminance) are not readable; they need low luminance.
- Many tools make it easy to validate contrast ratio according to the Web Content Accessibility Guidelines (WCAG) standard, determine the ideal colours for the readability of your texts and graphic elements, simulate colour blindness for your colours, and define a colour palette for the web theme. presentation in a way that is accessible to everyone.
- Add alt text to images and objects
AltText appears when you hover over an image or object and helps people who use screen readers understand the meaning of the images. Must be included for the following objects:
- Pre-designed images
- Charts (from Office 2010).
- Tables (from Office 2010).
- Dynamic Tables (from Office 2010).
- Shapes without text.
- SmartArt graphics
- Embedded objects
- Groups (all objects in the list except shapes must also have alt text when in groups).
- Pencil or freehand drawings.
- Audio and video files.
Decorative images have to be marked as such.
We must be careful with the images, graphics, icons and symbols that we use as they can be interpreted in different ways in different cultures and be annoying and even offensive to some people. See: Localization and web accessibility by Autonomous University of Barcelona
- Use simple table structures
By not using nested table structures or merged or split cells, navigation through the table is much easier. A table should have a simple two-dimensional structure so that people with disabilities can easily navigate and understand it.
The use of blank cells or rows or columns with entirely blank cells in a table can be misleading if screen readers are used to access the presentation, as it can lead the user to think that there is no more content to read in the table. To do this, the blank row or column must be deleted.
- Specify information in column headers in tables
Having clear information in the column headers helps put screen reader users in context and helps them navigate the table. We need to make sure that data tables have a header row. To do this, verify that the Header row checkbox is selected in Table designates > Table style options.
- Include subtitles for audio and video files
Audio, voice, and video media can communicate important information that may not be available to people with some disabilities. When inserting multimedia content into a presentation it is necessary to ensure that the content is available in alternative formats such as subtitles in videos, alternative text or transcripts of a narration in notes, which can be used by users with disabilities.
Recording a narration to the presentation allows visually impaired people to hear the content of the presentation. Writing narration as slide notes can benefit people who are hearing impaired or whose computers do not have a sound.
- Check that all slides have a title that is unique
People with vision limitations use the titles of the slides to navigate and select the slide they want to perceive, so it is essential that each one of them has a title and that it is unique; that is to say that it identifies each slide in a particular way. Slide titles should be meaningful and a useful way to convey the structure of your presentation to the reader.
To see the titles of all the slides, go to the menu View > Outline View, and a list of all the slides with the elements they contain appears.
- Check the reading order
Screen readers read aloud the content, shapes, or text on the slide in a specific order. It is important to check the reading order that screen readers will use on each slide so that it follows a logical order and make sense.
- Avoid including relevant information in the slide master or footer
Care must be taken as the slide master is not verbalised by screen readers, so be aware that it should not include elements that are considered important to the information. In the same way, the information included in the page footers is not verbalised, so they should not contain relevant data.
- Accessibility check of PowerPoint presentations
The Accessibility Checker is a tool that checks your content and points out any accessibility issues it encounters. It explains why each issue might be a potential problem for some people with disabilities. The accessibility checker also provides suggestions for solving the problems you encounter.
In PowerPoint, the Accessibility Checker runs automatically in the background while you're creating a document. If the Accessibility Checker detects accessibility issues, you receive a notification in the status bar.
To start accessibility checking manually, choose Review > Accessibility Check. The Accessibility panel opens, and you can now review and fix accessibility issues.