Why does the word for "high school" use 校 instead of 学?


I'm learning Japanese on Duolingo and they're starting to teach me some
vocabulary about schooling. Things like 大学, 中学, 小学, and... 高校?

I know that 学校 is the kanji spelling of "school," but why does "high school"
use the 校 kanji, whereas all the other forms use the 学 kanji? What's the
difference between these two kanji/why is one more appropriate for high-school
specifically?

* * *

James' answer below has informed me that 日本語 has abbreviations for some of its
words, in this case from 高等学校 to 高校. My question now becomes, "Why does 高等学校
get abbreviated to 高校, keeping the 校, but all other forms of school keep the 学
instead?"




First of all, 小学, 中学 and 高校 are abbreviations. The full (non-abbreviated)
forms are:

  * 小学校
  * 中学校
  * 高等学校
  * 大学

You can already see some inconsistencies. Only 高等学校 has two characters before
学. 大学 are officially 大学 and has no 校 in the first place! (The word 大学校 exists,
but [it refers to something
different](https://japanese.stackexchange.com/q/36002/5010).)

After the Meiji Restoration, the Japanese education system underwent repeated
reforms, which is too complicated to explain here (see [these
charts](https://www.mext.go.jp/b_menu/hakusho/html/others/detail/1318188.htm)).
Roughly speaking, 大学 was a very old word borrowed from Chinese, and it
remained unchanged. The name 高等学校 was established relatively later as a
special type of school for selected elites, and that's why it looks different
from 小学校/中学校. These words have different origins and histories, so it's no
surprising that they were abbreviated differently.

[学 and 校 both means _school_
anyway](https://japanese.stackexchange.com/q/15111/5010), so 高学 seems equally
reasonable as the abbreviation of 高等学校. I could not find why exactly 高学 was
not chosen, but I guess there were some practical reason in those days. Maybe
someone thought こうがく was confusing because there was already the word 工学
(engineering)?




First of all, 小学, 中学 and 高校 are abbreviations. The full (non-abbreviated)
forms are:

  * 小学校
  * 中学校
  * 高等学校
  * 大学

You can already see some inconsistencies. Only 高等学校 has two characters before
学. 大学 are officially 大学 and has no 校 in the first place! (The word 大学校 exists,
but [it refers to something
different](https://japanese.stackexchange.com/q/36002/5010).)

After the Meiji Restoration, the Japanese education system underwent repeated
reforms, which is too complicated to explain here (see [these
charts](https://www.mext.go.jp/b_menu/hakusho/html/others/detail/1318188.htm)).
Roughly speaking, 大学 was a very old word borrowed from Chinese, and it
remained unchanged. The name 高等学校 was established relatively later as a
special type of school for selected elites, and that's why it looks different
from 小学校/中学校. These words have different origins and histories, so it's no
surprising that they were abbreviated differently.

[学 and 校 both means _school_
anyway](https://japanese.stackexchange.com/q/15111/5010), so 高学 seems equally
reasonable as the abbreviation of 高等学校. I could not find why exactly 高学 was
not chosen, but I guess there were some practical reason in those days. Maybe
someone thought こうがく was confusing because there was already the word 工学
(engineering)?

