How does a studen log out so another student can start the same exam?
While there is not a log off for a student, you can accomplish the same thing by deleting the exam.
(3) Swipe that test to the left and see a red box appear on the right that says "Delete".
(4) Tap the red delete button.
This will let you delete the test even if it has not timed out. Then, you can re-download the exam for use with another student.