Classroom teachers have a dedicated copy of a course for each class section.  When you are ready to administer a quiz or test, you will need to un-hide those links so they are visible to the students.

To un-hide a quiz or exam, click the gear icon near the top-right corner of the screen and "Turn Editing On".  This will make additional links and options visible near each resource, and you can elect to "Show" or "Hide" the quiz and test elements.  When your students are finished, you can hide the links again, or leave them visible long-term.  When finished hiding or un-hiding elements, you can "Turn Editing Off" from the gear icon.

There is a walk-through of this process under the "Professional Development -> Common Administrative Features -> Giving Quizzes and Tests" module.

You can actually hide or un-hide any course resource (text, videos, or entire chapters) using this same process.