These same terms apply in the same way to the four years of a standard high school: 9th grade is freshman year, 10th grade sophomore year, 11th grade junior year, and 12th grade senior year.
In the US, a student in the eleventh grade is typically referred to as a student in the eleventh grade or as a junior. The vast majority of students who are classified as juniors take the SAT Reasoning Test and/or ACT in the second semester of their third year of high school.
freshmenIn the United States, ninth grade is usually the first year in high school. In this system, ninth graders are also often referred to as freshmen. It can also be the last year of junior high school. The typical age for U.S. 9th grade students is 14 to 15 years.