I am one of those people with low GPA but want to apply for graduate school in US. I am really having trouble with standardized tests in my institution. It's not uncommon for me to receive low grade in final exams(finals normally account for 60% to 70% percent of grading of corresponding courses) and this has led to a number of courses with poor grades that is already enough to ruin my GPA. It is not that I didn't spend time in studying, in fact I learned those courses quite well (perhaps, in other words, I am not a good test taker). I was initially thinking I should get the right GPA I deserve and was very angry with myself especially when I saw many of my peers could confidently gain much higher GPA than I do even with only a little understanding of course materials plus simply memorizing lecture notes by force(yes, our exams makes this kind of preparation really an effective way to get grades like 3.7/4.0 for most core courses). It seems to me like my classmates can have 3.7/4.0 with ease, but I was more likely to get only 2.7/3.0/3.3 even if I was well versed in coursework and fully prepared for exams. I talked to my classmates for help but they told me they were too surprised by my situation and don't know what I should do at all. I tried various methods to make a difference like making sure my homework/class attendance parts of scoring rubric are going well, even the above mentioned exam preparation strategy, but still received little improvement. I never successfully found a solution throughout my undergrad, and I really want to defend this shortcoming in my statement of purpose, but I have worries about this.
MY QUESTION IS: If I go ahead to explain this in my SOP, would it sound like merely an attempt to find an excuse? If your advice is "do it", is there anything I should not talk about regarding the reason I mentioned above(i.e. don'ts)?
*. Some additional information, I am applying physics graduate program. I have first author publication in physics which I think could help me address that my knowledge mastery of related maths and physics is not what my grade shows. But even so, my paper, of course, cannot address other poorly scored courses.