Kaizena, another tool (apart from Read&Write for Google) for staff to provide feedback to students within various Google apps, is now installed and available for staff and student use when logged into their Google accounts. Kaziena helps students, teachers, and administrators provide effective and relevant feedback for diverse learners. Its features include: text comments, voice comments, lessons (small micro-units of learning), and skills and rubrics.
Information and videos on getting started and using the add-on can be found at https://help.kaizena.com/en/collections/60518-kaizena-for-google-docs
Easy to associate micro lessons, another feature of the add-on, are described at https://www.kaizena.com/features/lessons
Below are a 2 minute overview video and one that showcases the feedback options: