On hiragana, romaji and pronunciation


I have heard a Japanese teacher explain how long vowels should be pronounced
and how they should be written when using hiragana. That's what I saw on the
whiteboard:

> がっこう - gakko **o** , ( _not_ gakko **u** )

Is it correct? I understand that the sound is pretty much the same. But if
it's gakko **o** , then the hiragana version should be _がっこお_ , which is not
OK.




Do you know there are several romanization systems, each of which treats long
vowels fairly differently? [This Wikipedia
article](https://en.wikipedia.org/wiki/Romanization_of_Japanese) is a good
starter.

**がっこう**

  * Nihon-shiki/Kunrei-shiki system: **gakkô**
  * Hepburn system: **gakkō** (although there are [many variants](https://en.wikipedia.org/wiki/Hepburn_romanization#Variations))
  * Passport-shiki system: **gakko**
  * [JSL](https://en.wikipedia.org/wiki/JSL_romanization): **gakkoo**
  * [Wāpuro style](https://en.wikipedia.org/wiki/W%C4%81puro_r%C5%8Dmaji): **gakkou**

If your teacher is using JSL, "gakkoo" is the correct Romanized spelling.
Nevertheless, the only correct spelling in hiragana is がっこう.




Do you know there are several romanization systems, each of which treats long
vowels fairly differently? [This Wikipedia
article](https://en.wikipedia.org/wiki/Romanization_of_Japanese) is a good
starter.

**がっこう**

  * Nihon-shiki/Kunrei-shiki system: **gakkô**
  * Hepburn system: **gakkō** (although there are [many variants](https://en.wikipedia.org/wiki/Hepburn_romanization#Variations))
  * Passport-shiki system: **gakko**
  * [JSL](https://en.wikipedia.org/wiki/JSL_romanization): **gakkoo**
  * [Wāpuro style](https://en.wikipedia.org/wiki/W%C4%81puro_r%C5%8Dmaji): **gakkou**

If your teacher is using JSL, "gakkoo" is the correct Romanized spelling.
Nevertheless, the only correct spelling in hiragana is がっこう.

