Many activities created in a unit will automatically add an item into the gradebook. It may be useful or necessary to hide the marks/grades for particular items either permanently or until after a certain date.
Two items that should be hidden are the unit total and the assessable category total. A savvy student will be able to calculate their totals by combining the results of all their assessments, but LEO is not where students should be getting this information. Grades are released through the student system after a moderation and approval process. Marks should not move much from what they have earned in their assessments, but the results in gradebook are not the definitive final marks.
It may be useful to hide other items that perhaps are formative or are not graded and are only cluttering up the gradebook.
For some activities it will be useful to set a release date for marks. An assignment's grade should be released no more than three weeks after the due date, for example. If a release date is not set, some students may get their results before others - with the results going out as each student's work is being marked.
From Grades > Setup > Categories and items click the 'Edit' next to the gradebook item and then 'Edit settings'. Under the 'Grade item' click 'Show more...' to bring up extra settings.
To hide the grades for an activity from students either permanently, or until you are ready to unhide them, tick the 'Hidden' check box.
Please note, with a Turnitin assignment, the marks still may be accessible to students if they go to the assignment directly. Ensure you set a release date in the Turnitin assignment as well, by setting the 'Post Date' in the Turnitin assignment settings.
To add an automatic release date for the activity's grades, tick the 'Enable' check box and add the date.