Once time is up or students have completed your assessment, you can formally Finish your assessment. This means students will no longer be able to access the assessment.
To Finish an Assessment:
Navigate to the class the assessment is launched from
Tap into the corresponding assignment
From the Shared Items list, open the launched assessment. (You will see it reads "In Progress" under your assessment name.)
Tap the Finish Activity button at the top of the Live Results screen.
You'll then be able to export reports and share results with your students if you choose.