Official Google Blog had a post about the accessibility features of Chrome, Google Apps, and the Android OS. Included in that post is a link to the Google Apps accessibility guides for blind and low-vision users. The guides cover Gmail, Drive (including Doc, Sheets, and Slides), and calendar. If you're a Google Apps for Education domain administrator you will also want to take note of the Administrator Guide to Accessibility that includes recommendations for control panel settings as well as recommendations for screen readers.
You can download this guide for personal use, not for redistribution, here.