Several links to guides and lists of resources for accessible teaching from the DO-IT Center out of the University of Washington.

The goal of the Accessibility Toolkit – 2nd Edition is to provide resources for each content creator, instructional designer, educational technologist, librarian, administrator, and teaching assistant to create a truly open textbook—one that is free and accessible for all students.

WAVE is an accessibility evaluation tool from WebAIM. Just enter a url into the tool and WAVE will provide you with a report of adherence with Web Content Accessibility Guidelines (WCAG) and suggest changes for improvement. 

Links to a Google slide presentation by CAST representatives on designing accessible Open Educational Resources.