For critical thinking and portfolio assignments, the grading rubric can be found on the bottom of each assignment page. Just click the Assignments link at the left side of your course page, navigate to the specific assignment you're looking for, and scroll to the bottom of the page.
For discussion board assignments, click the Discussions link at the left side of your course page, then click on the discussion forum you're looking for. At the top of each forum click the box to have the option to view the rubric.
Grading rubrics can be found on the Grades page (located at the left). After you are on the Grades page, you can click on the four small boxes next to the assignment grade. This will bring up a a description of the criteria for the grade as well as the rating. The rating section will break down exactly what each section is worth.
If the instructor has graded the assignment you will be able to view each criteria and the points awarded.