他是学生；他是大学生

[MoniqueMaRie]

How do you know in the sentence 他是 大 学生 that the translation must be "he's a college student" instead of "he's a big student (pupil)" ?
他是学生 = he's a student (pupil)
大 = big

Do you say
他是个大学生 = he is a big pupil
with the 个 to show that the 大 is an attribute?

[qyanw35f]

Actually, you're almost there to get the point:
Yes， 学生 is student.
In China, we categorize "students" by what school they're in - Elementary school, middle school, high school, and college/university. When it comes to describing students, we also like to use three characters to spit out a word for the consistency.
小学生 "small" student - elementary school student
中学生 "middle" student - middle school student
高中生 "high-middle" person- high school student (because high school is still somewhat middle school but the higher education for middle school? )
大学生 "big" student - college student

If you're curious about "students" in kindergarten, they're not considering "students". Because worldwide, kids before 6 years old are not forced to be educated with textbooks. They're there to hangout with friends, grow, and develop their natural senses. So we call them 小朋友 (little friend).

[McGonnagle]

This applies both in Japanese and Chinese: Here, "大" is not an adjective, but a part of the word "大学" (university). In other words, "大" is not used to describe the student as "big" in a physical sense.

"大学生" is a compound word that corresponds to "college student" or "university student" in English.

When you want to express that someone is physically "big," you would use expressions such as "个子高" (tall), "身体壮" / "很壮" (muscular), "结实" (fit), or "胖" (fat).

Since the English word "big" has a wide range of meanings, it can be difficult for both Japanese and Chinese speakers to understand what exactly "He is a big student" means.

Additionally, "他是大学生" and "他是个大学生" have the same meaning, but the former is a more formal and standard expression, while the latter is a more casual and colloquial way of saying it.

In Chinese, to maintain the rhythm and balance of the sentence, colloquial language often uses measure words like "个," "些," and "点."

[McGonnagle]

@qyanw35f explains this from a morphological perspective.

The characters 小 (small), 中 (middle), 高 (high), and 大 (big) each function as morphemes that carry their own basic meanings.
So, when broken down and translated literally, we get:

小学生 → small-student (elementary school student)
中学生 → middle-student (middle school student)　　
高中生 → high-student (senior high school)
大学生 → big-student (college or university student)

From the standpoint of word formation and morphological structure, this interpretation makes sense and is technically correct.
　　
While I’m approaching this from a semantic perspective — focusing on the meanings of 小, 中, 高, and 大 within the context of the full words.

While these characters do carry meanings like "小small," "中middle," "高high," and "大big" as individual morphemes, in these compound words they are not referring to physical size or literal bigness. Instead, they indicate levels of education.

Specifically:

小 refers to the elementary school level
中 refers to the middle school level
高 refers to the senior high school level
大 refers to the college or university level

In this sense, these terms reflect educational stages within the school system.

Therefore, the "大" in "大学生" doesn’t mean "big" in a physical or literal sense — rather, it functions as a marker of higher education level.

[MoniqueMaRie]

In China, we categorize "students" by what school they're in - Elementary school, middle school, high school, and college/university. When it comes to describing students, we also like to use three characters to spit out a word for the consistency.
小学生 "small" student - elementary school student
中学生 "middle" student - middle school student
高中生 "high-middle" person- high school student (because high school is still somewhat middle school but the higher education for middle school? )
大学生 "big" student - college student

So it's more important to always have three characters than to emphasise learning 学 ?

I am now puzzled about 高 中 生 .
I would have thought it should be 高中学生. (High middle student)

[McGonnagle]

In China, we categorize "students" by what school they're in - Elementary school, middle school, high school, and college/university. When it comes to describing students, we also like to use three characters to spit out a word for the consistency.
小学生 "small" student - elementary school student
中学生 "middle" student - middle school student
高中生 "high-middle" person- high school student (because high school is still somewhat middle school but the higher education for middle school? )
大学生 "big" student - college student

So it's more important to always have three characters than to emphasise learning 学 ?

I am now puzzled about 高 中 生 .
I would have thought it should be 高中学生. (High middle student)

"高中学生" = "High school student" (more formal, slightly literary)
"高中生" = "High schooler" or "high school student" (more colloquial and natural)

[ararat-tempest]

there's also, 他是大个学生。
he's a tall (maybe strong) student.

[McGonnagle]

Also, 他是高个子学生。(He is a tall student.)