Returning a lesson is what releases marks and feedback to students. Until you do, they see their work as submitted but not marked.
Moderate first
Open the classroom, go to Assignments, click the assignment and then the lesson. Then pick your route:
Student by student: on the Students tab, click a name to open that student's whole submission, then click Next student to work down the class. See Reviewing a student's submission.
Question by question: on the Blocks tab, click a question to read every student's answer to it. See Moderating one question across the class.
On a long answer, the ticks show which phrases earned marks and the Marking breakdown lists every criterion with the reason, so you can see why a mark was given before you accept it.
Disagree with one? Click Adjust mark or Edit feedback, change it, and click Save. This works on long answers and Legacy editor free responses. If the mark scheme itself is the problem, fix it once and remark the class: see How to update mark schemes and remark submissions.
To keep a copy of a student's marked work, click Download PDF on their submission (New editor lessons). See Download a marked copy.
When you are done, click the lesson name in the breadcrumb at the top to get back to the Students tab.
Then return
Tick the students you are ready to release and click Return submissions.
Their lesson switches to Returned and they can see their marks and feedback.
If the lesson's feedback type is On return, this is the moment students see anything at all.
What your students see
Each student gets a notification in their Inbox, for example Returned Photosynthesis Basics (Grade 9 Natural Sciences)., with a Review feedback button that opens the lesson. Students who have turned on the daily digest email get it there too.
Return the same student again after a resubmission and the new notification replaces the old one. Lessons with Instant or On submission feedback are returned automatically, so they do not send a notification: the student sees their feedback as soon as they submit.