I just sign in on my child'support account.

Update: Google Classroom now allows guardians to sign up to receive a weekly digest email. This will show you recent assignments done via GoogleClassroom. You still can't see yourDC's feed, but this should help.

Once your kid accepts the invitation, OP, then s/he can access Google Classroom. It's simply a platform for housing lessons - mostly flipped in my case - and other resources. Sometimes there's an online discussion component.