This document explains how to prevent students from seeing a quiz grade. This may be useful in situations where the instructor needs to grade part or all of the quiz manually.
On the Assessment tabbed page, by "Automatic Grade", make sure the box
"Allow attempt score to be set as graded immediately upon completion" is not checked.
Go to grade the quiz and make sure the box(es) under Published for the "attempt" number(s) for the student(s), are not checked. If necessary, un-check the box(es) and press Save or Save and Close.
If there is a Grade item associated with the quiz, make sure students cannot view the item.
Otherwise, they will be able to see the quiz score through Grades and View Progress.
Go to edit the Grade item in the "Manage Grades" area of the Grades tool. Select the "Restrictions" tabbed page and make sure Hide this grade item is selected by "Visibility".