1.
middle school student, junior high school student
A student attending 中学校, which covers grades 7-9 (ages 12-15) in the Japanese education system.
娘は中学生です。
My daughter is a middle school student.
中学生のとき、部活でテニスをしていた。
When I was in middle school, I played tennis in my school club.
この映画は中学生でも分かる内容です。
This movie has content that even a middle school student can understand.
FORMATION:
中学 (middle school, abbreviation of 中学校) + 生 (student). The suffix ～生 is used for students at all levels: 小学生 (elementary), 高校生 (high school), 大学生 (university).
JAPANESE SCHOOL SYSTEM:
- 小学校 — elementary school (6 years, ages 6-12)
- 中学校 — middle school (3 years, ages 12-15)
- 高校 — high school (3 years, ages 15-18)
中学生 is often abbreviated to 中学 in casual speech: 中学のとき (when I was in middle school).