I couldn't believe this form Microsoft's own accessibility guidance for the latest mac offerings: "Hear most menu commands, options in dialog boxes, and other elements on your computer screen. VoiceOver does not work with the contents of the main document window or the ribbon. For example, VoiceOver does not read your text in a document."
Deliver the PowerPoint as a finished product. In other words, display the presentation embedded in a web browser window. Avoid forcing students to download the presentation onto their computer if at all possible. Downloading presents all kinds of problems - for example, what happens with embedded audio and video files.
Text is found in many places on your computer, such as in windows and dialogs, in content areas like webpages and help files, and in documents. This chapter explains how to use VoiceOver to read, select, and edit text.