Learn Hardcore Japanese: koukou de nihongo wo benkyousimasu.

Listeners automatically understand “I” from the situation, the conversation topic, or who is speaking. This omission is very natural in Japanese and happens all the time, especially with 私.

Why does 高校 use the particle で? Why not に?

で marks the place where an action happens.
In 高校で日本語を勉強します。, the action 勉強します (study) happens at/in high school, so we use:

高校で = at high school / in high school

Contrast this with に, which often marks:

A destination (where you go to)
- 高校に行きます。 – I go to high school.
Or an existence/location (where something/someone is)
- 先生は高校にいます。 – The teacher is at the high school.

So:

高校に行きます。 – I go to the high school. (destination)
高校で勉強します。 – I study at the high school. (place of action)

For “do something at/in a place,” で is the normal choice.

Why is を used after 日本語? Could I use が instead?

を marks the direct object of an action – what the verb is acting on.

日本語を勉強します。
→ The verb is 勉強します (to study).
→ What do you study? 日本語 (Japanese).
→ So 日本語 is the direct object → use を.

Using が here would be wrong with this verb pattern.
Some verbs (like わかる, 見える) naturally take が, but 勉強する takes を for what you’re studying.

So:

日本語を勉強します。 ✅
日本語が勉強します。 ❌ (unnatural / ungrammatical in this meaning)

What tense is 勉強します? Does it mean present or future?

The polite -ます form in 勉強します is a non‑past form.
In Japanese, this one form covers both:

Present / habitual:
- I study Japanese in high school (as a regular fact).
Future:
- I will study Japanese in high school.

The exact meaning depends on context:

Talking about your current situation:
→ I study Japanese in high school.
Talking about next year’s plan:
→ I will study Japanese in high school (next year).

Japanese usually doesn’t separate “I study” vs. “I will study” with different verb forms; context and time expressions (like 来年, next year) make the meaning clear.

Why does the verb 勉強します have to go at the end? Can I change the word order?

Japanese word order is generally:

[place/time/etc.] + [object] + [verb]

So:

高校で (place)
日本語を (object)
勉強します。 (verb)

The verb almost always comes at the end in standard Japanese sentences.

You can move most other parts around for emphasis, as long as the particles stay attached to the right words:

日本語を高校で勉強します。 (Still OK)
高校で日本語を勉強します。 (Most natural here)

But putting the verb in the middle, like:

❌ 勉強します高校で日本語を。

would be incorrect or sound very strange.
So: you can shuffle the parts with particles, but keep the verb at the end.

What level of politeness is 勉強します compared to 勉強する?

勉強します is the polite form (ます‑form).
- Used when talking to teachers, strangers, coworkers, or in most normal everyday conversations unless you’re very close.
勉強する is the plain/casual form (dictionary form).
- Used with close friends, family (often), or in informal writing, inner thoughts, dictionaries.

Same meaning (“to study”), different politeness level.

So:

高校で日本語を勉強します。
→ Polite: what you’d say to a teacher.
高校で日本語を勉強する。
→ Casual: what you might say to a close friend.

Can I omit 日本語 and just say 高校で勉強します。? Does it still sound natural?

Yes, you can omit 日本語 if it’s clear from context what you’re studying.

高校で勉強します。
→ I study at high school. / I will study at high school.

People will usually assume you mean studying school subjects in general, or something that was mentioned earlier in the conversation.

This is very natural in Japanese. Just like the subject 私 can be dropped, so can objects like 日本語, as long as both speakers already know what you’re talking about.

How do I say “I studied Japanese in high school” instead?

Use the past tense of 勉強します, which is 勉強しました (polite past).

高校で日本語を勉強しました。
→ I studied Japanese in high school.

Breakdown:

勉強します – (non‑past) study / will study
勉強しました – (past) studied

If you want casual speech:

高校で日本語を勉強した。
→ same meaning, but plain/casual form.

Where do I put time expressions like “every day” or “from next year” in this sentence?

Time expressions usually go near the beginning of the sentence, before the verb, often before or after the place phrase. Both orders are common and natural.

Examples:

毎日高校で日本語を勉強します。
→ I study Japanese at high school every day.
高校で毎日日本語を勉強します。
→ At high school, I study Japanese every day.
来年高校で日本語を勉強します。
→ I will study Japanese in high school from next year / next year.
高校で来年日本語を勉強します。
→ Also possible, but (3) is more typical here.

General pattern:

[Time] [Place] [Object] [Verb]
[Place] [Time] [Object] [Verb]

But keep the verb at the end.

What’s the difference between 高校で日本語を勉強します。 and 日本語は高校で勉強します。?

Both can be translated as “I study Japanese in high school.”, but the focus (topic) is slightly different.

高校で日本語を勉強します。
- Neutral, simple statement.
- Feels like you’re just stating the fact:
  → I study Japanese at high school.
日本語は高校で勉強します。
- 日本語は makes “Japanese” the topic.
- Implies a contrast or emphasis, like:
  - As for Japanese, I study it in high school (not somewhere else).
  - Japanese, I study in high school (but maybe other subjects somewhere else).

So は doesn’t change the basic meaning, but it adds a nuance of “as for…” or contrast.
Use 日本語は高校で勉強します。 when you want to highlight “Japanese” as the topic or contrast it with something else.