You can either:
Open all assessments
or Open individual assessments
How do I open all assessments?
To open all assessments:
Open the Feedback section
Click Actions > Open assessments
Click Open all assessments
How do I open an individual assessment?
To open an individual assessment:
Click on the name of the person being assessed
Open their Settings tab
Click Reopen assessment...
Confirm that you wish to reopen the assessment.