How to improve the readability of PDFs for Additional Support Needs

In a recent post by my colleague Allan Wilson, Information Officer at CALL Scotland, Allan highlighted the Books for All database, which provides access to text for pupils who find it difficult or impossible to read ordinary printed books, e.g. pupils with a print disability and/or mobility difficulty who are unable to turn pages.

Books for All logo
A large proportion of the digital books are in Portable Document Format, otherwise known as PDF. An advantage of the PDF format is that it can be used across a range of computers and tablets, such as Windows, Macs, iPads and Androids. Although many computers have a built-in PDF reader, a popular and reliable PDF reader is Adobe Acrobat Reader, which is free to download.

Adobe Acrobat Reader has numerous tools that can improve the readability of PDFs which can be particularly useful for those children who have a print disability such as dyslexia, or a visual impairment. The following offers some hints and tips in improving the readability (and accessibility) of PDFs by using the built-in tools in Adobe Reader.

If you find the tips in this blog post handy, head on over to the CALL Scotland website where you can download a poster summarising the features of Adobe Reader!

Changing the background colour

Black text on a white background, as standard in many paper books, can be a barrier to many children, particularly those who experience visual stress or scotopic light sensitivity – when the letters and words on a page appear is if they are moving or even back to front.

This can be easily remedied by changing the background colour of the pages. Some children use a colour overlay which is placed over the page, however, in Adobe Acrobat Reader it is easy to change the background colour of a PDF:

  1. Choose Edit from the menu bar.
  2. Choose Preferences at the bottom of the drop-down menu.
  3. When the Preferences Pane appears, choose ‘Accessibility’ from the left pane and tick Replace Document Colours with a colour of your own choice.
  4. Finally, click 'OK'.

screenshot of someone changing the background colour on a PDF


The illustration below shows how changing the colour background can make a difference. High contrast colours are also available to support children with sight difficulties. 


A screenshot of different background colours in a PDF


Using Read Out Loud and text-to-speech

As well as changing the background colour Adobe Acrobat Reader also has a built-in text reader – Read Out Loud.

Read Out Loud is activated from the 'View' menu and is located at the bottom of the drop-down menu. Read Out Loud can be set to either read a single page, the whole document or you can click a single section of text (highlighted by a black box). 


A screenshot of someone accessing the Read Out Loud feature


For best results, a quality computer voice is recommended as it helps to improve the listening experience. If you work in the public sector, you can download the Scottish Voices, Heather and Stuart (and Ceitidh for Gaelic books) for free from The Scottish Voice.

With Adobe Acrobat Reader you can set a voice of your choice, although you may be limited to the computer's default voice if you haven’t previously installed other computer voices.

To set a computer voice, follow the steps below:

  1. Choose Edit from the menu bar.
  2. Choose Preferences at the bottom of the drop-down menu.
  3. When the Preferences Pane appears, choose ‘Reading’ from the left pane. If 'Use the default voice' is selected, you may need to untick the box, so you can choose a voice from the drop-down menu.
  4. Finally, click 'OK'. 


Screenshot of someone selecting a computer reading voice


Read Out Loud is a useful tool for reading text aloud but it is limited. Natural Reader is a free text-reader – select the text you want to be spoken aloud and press the large play button. The text is highlighted in time with the voice as it is spoken aloud. Natural Reader also supports the Scottish Voices. 


Screenshot from Natural Reader


Supporting children with sight loss – magnification

Using a combination of colour backgrounds and text-to-speech can be a transformative experience for some children who struggle with text. However, Adobe Acrobat Reader also includes a range of tools to support children with sight loss.

Under 'View' and 'Zoom' you can increase or magnify the text size up to 400% and beyond – see the illustration below. 


A screenshot of someone increasing the magnification in a PDF


Screenshot of someone using the plus and minus buttons to magnify text
Increasing text size can also be accessed from the menu bar by clicking the 'plus' circle' to increase text size and the 'minus' circle to decrease the size. 

This shortcut is useful to quickly zoom in and out of a document until a suitable size is found.  

One thing to bear in mind is that when text on a document is magnified to high levels the text can start to 'run off' the page.

This entails adjusting the horizontal and vertical scroll bars which can be frustrating and time-consuming. However, Adobe Acrobat Reader includes a great tool to overcome this. 

Page 'Reflow' (under View and Zoom) reflows the text so it fits on the page, regardless of the size. A child with sight loss can have large text on the screen, improving readability.


A screenshot of someone using the Reflow option


Other magnification options can be found under 'Zoom' such as 'Pan & Zoom' – don’t be scared to experiment with the various tools. 

Supporting Children with mobility difficulties

For some children using a standard mouse can be problematic, i.e. clicking to scroll up and down and/or turn pages. Although there are other mouse alternatives Adobe Acrobat Reader has a built-in automatic scrolling tool, 'Automatically Scroll' – View and Page Display.

Automatically Scroll can also be controlled with a keyboard shortcut key 'Shift + Ctrl + H'.


A screenshot of someone selecting the auto scroll function

When Automatic Scroll is turned on the speed and direction of movement are controlled by the Up and Down Arrow Keys on the Keyboard. The 'Alt' key will pause and restart Automatic Scrolling.

A benefit of these tools is that they can be used in combination with each other, for example, changing the background colour and using Read Out Loud. Automatic Scrolling can also be used in conjunction with Zoom and Page Reflow, similar to a video magnifier device traditionally used by those with low vision.  Another additional option is to combine Automatic Scrolling with Zoom, Page Reflow and Read Out Loud, so the document is read aloud while it scrolls.

There's more to PDFs and Adobe Acrobat than you think!


Enjoyed this blog post by Craig? You can find out all about the support that CALL Scotland can offer pupils with ASN in this blog post. After that, why not check out all of our blog posts about Additional Support Needs, where you can find out about CALL's symbolised resources to help communication, Listening Books' range of free audiobooks for schools, and more!

CALL Scotland have made a handy poster summarising the features of Adobe Acrobat Reader - you can download it at their website.

The Bookbug Picture Book Prize is a fantastic project to help you inspire young pupils to read for pleasure, and CALL Scotland provide lots of resources to help pupils with Additional Support Needs take part in the prize. Find out more by heading over to the Bookbug Picture Book Prize homepage.

Top image, cropped and resized, by Kelly Sikkema on




Craig Mill

Craig is the Digital Inclusion Technology Advisor at CALL Scotland.