It's helpful to know a few things about grade items that you hide in the gradebook....

First (and most importantly), our gradebooks are set up by default to factor hidden scores into students' category and course totals. Points for hidden items will still count.

Second, hiding an activity like an assignment or a forum in your gradebook results in students not being able to see any of your feedback or access any files that you may have returned to them. Also, if you hide a gradable assignment, quiz or forum on the course main page, the item will also be hidden in the grade book

Depending on why you'd like to hide scores, there are a few different ways of dealing with items you don't want to have displayed. Here are some options:

Hiding Scores Until All Grades Assigned

If you want to hold off displaying grades until all scores have been entered, edit the grade item in the gradebook and select Show more... to enter a "hidden until" option to release all grades at once at a future time.

Item No Longer Assigned

You can hide existing assignments or quizzes on the main course page and they will be hidden from students in the gradebook—you'll still see them in your gradebook, but students won't. The points associated with them will still be included in the total points you can see but will not be factored into the total possible points for students. To eliminate those points from your view, create an "ungraded items" category, set its aggregation method for Simple weighted means and make the Maximum grade 0. Shift your hidden, unwanted items into that category and your course total should reflect the total possible points on which you intend to base the course assessment.

Bonus: What Do Students See?

If you're curious about what students see when they check their grades, click on the User report link in the drop-down menu on the grader report page. Search on a student's name to see a close approximation of what students see (naturally, students see only the grades assigned to them). Note that the total possible points is based on the items graded for each student, so course totals may vary from student to student.