When students submit work in Google Classroom a notification is not created. This can be an issue when work is submitted late or when students make updates to their work that need to be commented on.
Leave a Private Comment
When a private comment is left in a Google Classroom assignment the teacher automatically receives an email notification. The teacher can view the private comment right in the email. The email also contains a direct link to the assignment. The link in the email makes it easy for the teacher to locate the assignment needing to be assessed.
@MrOrtlinghaus on Twitter shared his directions for doing this on an iPad.