If you want to leave simple feedback for your students, you can leave a text comment directly from the Gradebook. If you want to annotate or leave audio/video feedback you can use Speedgrader.

Go to Grades

Locate the student name and assignment where you want to leave a comment and or grade. Click the Gradebook cell and click the Grade Detail Tray icon [newGradebookTrayIcon].
Input the grade in the Grade out of... section and type your comment in the Comments field, and then click the Submit button.

When there is more than one comment for an assignment, comments will be listed in chronological order with the oldest comments appearing at the top and the newer comments appearing near the bottom.

After leaving a comment(s), you have the ability to either delete your comment or make edits. The time stamp of the edited comment will indicate the comment has been edited.