1. The first step is to open Google Classroom and click to select a class

2. Scroll up and click settings

3. Scroll down and click Add grading scale

4. Click to select Proficiency,  Letter grades, 4 point scale or Create grading scale. 
For this example, I am choosing Letter Grades. 

5. Scroll down and click the drop down arrow next to Grade calculation

6. Click to select Total points or Weighted by category. For this example, I am choosing Weighted by category. 

7. Click to toggle on Show overall grade to students

8. Click Add grade category

9. Scroll down and type Grade category

10. Click Percentage

11. Type Percentage

12. Repeat steps 9-11 to add additional grade categories and percentages. Make sure your categories add to 100%. Click Add grade category. 

13. Scroll up and click Save

14. That's it, You're done. 

Interactive tutorial