Emails with information about their learner's classwork can be sent to parents. You can only add parents to learners in Classroom if you have a G Suite for Education account, not a personal one. However, because the G Suite version is used in the majority of educational settings, this should not be a problem for teachers who want to use this feature. It's a terrific approach to keep parents informed about their child's assignments and whether or not they're keeping up with their work.