我今年要升國中三年級怎麼說

Michael,For this sentence can we say "I'm going up to the third grade of junior high school this fall."?

國中三年級 = 美國的九年級I will be in the ninth grade this year. 或 I will be a ninth grader this year.

順道一提:國中 = junior high school = middle schoolI'll be in junior high school.I'll be in middle school.