Use of Grade Levels Instead of Age [closed]
Solution 1:
As an American, I can say that public schooling in the U.S. represents for us a kind of social coming-of-age system (especially during the high school years, which usually encompass the ages of 14-18), and as such is emotionally significant in some odd way.
Additionally, grade levels group us in ways that ages sometimes do not. Due to "cutoff age" rules, one grade—10th grade, for example—will typically have students who start the school year at age 14 or 15 and end it at ages 15 and 16, respectively, depending on their birth dates. Therefore, "when I was in 10th grade" is a time period relatable due to its sociological circumstance rather than a particular age. (BTW, I have no documentation to back this up; I am just musing based on my own experiences.)
Solution 2:
Not everyone is the same age in the same grade.
Grades are more meaningful as it indicates what things you were studying and your social interactions at that age.