As a teacher, you can get a free premium account for this extension by completing the form on this link. The premium version provides the same text to speech, dual highlighting, and translator features. It also includes supports for Google Docs, specifically, multi-highlighting options for active reading, extracting highlights, a vocabulary chart, a regular and picture dictionary, and word prediction. This Quick Reference Guide will provide more details about the features.
In order to download this extension, you need to be logged into your Chrome account in the aurorak12.org account. Next, you can go to the Chrome Web store or click on this link to download it.
Check out this Read & Write for Google Presentation for more details on how this tool can help you in the classroom. Feel free to contact your Ed Tech Coach if you need help