When you grade Writing lessons, you'll see that you have the option of selecting Quick Score or Rubric Score.
Use the Quick Score to quickly and easily give students feedback on their writing. You may provide feedback and assign a personal growth focus to help students determine where they should concentrate their efforts on their next assignments. You can score assignments on a 4-point or 5-point scale with Quick Score.
Use the Rubric Score to provide consistent, standards-aligned feedback. In addition to providing input on your students' writing overall, you may include additional, specific comments on each component of the rubric. As in the Quick Score method, you may also assign each student a personal growth focus.
For more explicit instructions on how to grade Writing lessons via both of the scoring mechanisms described above, see here.