There are two places in Workspace where you can choose to return work to students. In both of these places, you can return either for further edits, or as the final assessment, and you can choose to include a grade or not.
The first method is on the evidence card itself. In the Activity Status area on the card, select 'Submitted' - a pop-up will show, listing all evidence submitted by students. You can add a grade/assessment in the box (or leave it blank) and then choose whether you want to return this for further editing by the student, or return it final (in this case the student will not be able to submit this evidence again):
There is a Grade Sheet available for each published Workspace, which can be accessed by clicking "Grade Sheet". This is saved in the Workspace folder on the teacher's Google Drive and contains a list of all students, groups, and evidence cards along with any grades the teacher has issued through Workspace.
Another way to return evidence is to go to the Activity Summary page, where you can quickly open and return all work. The procedures and buttons for returning and grading work are the same.
See below for an example of how grades show to a student on their card in the Workspace: