You can use a Notes column in the Gradebook to keep track of extra information in your course, such as SIS IDs or just general student notes. The Notes column is not visible to students.
Note: Instructors can only show and hide the Notes column. Admins can use the API to create additional columns, but they cannot be hidden.
To make a comment, click the note field for the appropriate student  and enter your note in the text field . The note field allows up to 255 characters. To save your comment, click the Save button .
View your comments in the Notes column. You can view the full comment by resizing the column or re-clicking the notes text field.
Note: When you navigate away from the Gradebook, any changes to the size of the columns will be lost.
Hide Notes Column
To hide the Notes Column in the Gradebook, click the Settings icon  and click the Hide Notes Column link .
Note: You can toggle between the show/hide notes column link without losing your notes.