Install a screen reader

Welcome to the screen reader introduction! If you haven't already, please install a screen reader. On windows, we recommend NVDA. VoiceOver comes pre-installed on macOS. It can be enabled by navigating system preferences, or quickly with command+f5.

Feature set

Now that a screen reader is installed, familiarize yourself with its features. Screen readers provide numerous strategies for finding and reading content on the page. But every one is different. Below are links to documentation about common features of each of PhET's supported screen readers. Screen readers work best on particular browser combinations. PhET only supports the following screen reader and browser combinations: JAWS on Chrome, NVDA with Firefox, and VoiceOver with Safari.

NVDA key commands
JAWS key commands
VoiceOver key commands

Mobile VoiceOver

VoiceOver also comes installed on iOS devices. Instead of using VoiceOver with a keyboard, reading is done with gestures. This includes swiping your finger (or multiple fingers) to read through content on the page. Swipe right to read through content, and left to read backwards. Activate buttons by double tapping on the screen once a button is focused. Additional gestures and features of mobile VoiceOver can be found at this link.

Standard tablet VoiceOver gestures

Practice using the screen reader

Now that you are aware of common screen reader features, practice reading through the above content. Try reading through individual lines and jumping between headings and links. Once you are familiar with that, try navigating and using the form elements below to understand how AT read things.

Typical range slider:

Physics Chemistry Math

Typical radio button group

Reading Modes

Screen readers have two different modes for reading called "document mode" and "forms mode". In "document mode", you are free to use all of the navigation strategies you have learned about to read sentences, and find headings, buttons, lists, and so on. In "forms mode", all of those strategies are disabled and keys are used to interact with the focused element. For example, when you navigate to the above slider, your screen reader might beep or say "forms mode on", to let you know that the arrow keys will change the value rather than read other information.


Sometimes the screen reader needs to announce that something happened on a page without your input. These are called alerts and are used extensively in PhET sims. After pressing the button below, an alert will trigger, and the screen reader will announce that immediately even though focus is on the button.

(Thanks, Random Fact Generator)