Learn Hardcore Japanese: tyourei ha hatizi ni hazimarimasu. - The morning assembly starts at eight o'clock.

Schools: Students gather in the morning for announcements, speeches, singing the school song, etc.
Companies / offices: Workers stand together for short announcements, safety reminders, company motto, etc.

So 朝礼は八時に始まります。 is something you’d hear at a school or workplace.
Translating it as “The morning assembly starts at 8:00.” or “Morning meeting starts at 8:00.” is natural in English, but 朝礼 is more fixed and formalized than many casual Western “morning meetings.”

Why is は used after 朝礼? Could it be が instead?

In 朝礼は八時に始まります。, は marks 朝礼 as the topic of the sentence:
> As for the morning assembly, it starts at 8.

If you change it:

八時に朝礼が始まります。
Here が marks 朝礼 as the subject and puts more focus on what starts at 8.
→ “At 8 o’clock, the morning assembly starts.” (emphasis on it being 朝礼).

Nuance:

朝礼は八時に始まります。
→ Neutral explanation about 朝礼’s schedule. “Speaking of the morning assembly, its start time is 8.”
八時に朝礼が始まります。
→ More like an event report: “At 8, (what happens is that) the morning assembly starts.”

Both are grammatically correct; は makes it sound like a general statement about 朝礼, which fits a schedule explanation.

Why do we use the particle に after 八時? Could I use で or nothing instead?

に after a time expression marks a specific point in time:

八時に = at 8 o’clock

General rule:

Use に with specific times/dates:
- 三時に (at 3:00)
- 金曜日に (on Friday)
- 一月一日に (on January 1st)
Often omit に with very general time words like:
- 今日(に) (today) – usually without に
- 明日(に) (tomorrow) – usually without に
- 毎日(に) (every day) – almost always without に

You cannot use で for plain time like “at 8 o’clock.”
で is for location of an action or means:

学校で勉強します。= I study at school.
電車で行きます。= I go by train.

So 八時に始まります is the natural way to say “starts at 8 o’clock.”

What’s the difference between 始まります (はじまります) and 始めます (はじめます)?

They are a classic intransitive vs. transitive pair:

始まる / 始まります – intransitive (“to begin / to start” on its own)
- Subject is the thing that starts.
- 朝礼が始まります。= “The morning assembly starts.”
始める / 始めます – transitive (“to begin [something]” / “to start [something]”)
- Someone does the starting to something.
- 先生は朝礼を始めます。= “The teacher starts the morning assembly.”

In your sentence:

朝礼は八時に始まります。
→ “The morning assembly starts at 8.”
No doer is mentioned; it just begins at that time.

If you wanted “The teacher starts the morning assembly at 8,” you’d say:

先生は八時に朝礼を始めます。

The verb is in “present tense” (始まります), but we’re talking about a scheduled event. How can that mean “(it) starts at 8” in general or in the future?

Japanese has a non-past form (here: 始まります) that covers both:

present/habitual: things that regularly happen
future/scheduled: things that will happen

So 始まります can mean:

“starts / usually starts” (habitually)
“will start” (when talking about a future schedule)

In 朝礼は八時に始まります。, context tells us:

As a general rule or on the schedule, “The morning assembly starts at 8.”

For a specific future case (e.g., tomorrow), people still commonly use the same form plus a time phrase:

明日、朝礼は八時に始まります。
→ “Tomorrow, the morning assembly will start at 8.”

So you don’t need a special future tense; the non-past 始まります handles it.

How would I say this sentence more casually, without the polite ます form?

The verb 始まります is the polite “-ます” form of the dictionary form 始まる.

Here are the main forms:

Polite non-past: 始まります
Plain (casual) non-past: 始まる
Polite past: 始まりました
Plain past: 始まった

So the casual version of the sentence is:

朝礼は八時に始まる。
→ Casual, used with friends/peers/in writing like notes to yourself.

Compare:

朝礼は八時に始まります。 – polite, for teachers, bosses, formal situations.
朝礼は八時に始まる。 – plain/casual.

Can I say 八時から始まります instead of 八時に始まります? What’s the difference between に and から here?

Both are possible, but the nuance is slightly different:

八時に始まります。
→ “It starts at 8 o’clock.” (focus on the starting point in time)
八時から始まります。
→ “It starts from 8 o’clock (on).”
Implies that from 8 onward, it is in progress.

In practice:

For schedules, both are used a lot:
- 授業は九時に始まります。
- 授業は九時から始まります。
  Both are fine; から may sound a touch more like “from 9 onward.”

You can even combine both for emphasis on the exact starting point:

朝礼は八時ちょうどに始まります。
→ “The morning assembly starts exactly at 8:00.”

Does 八時 mean 8 a.m. or 8 p.m.? How do I say it clearly, and how do I say other times like 8:30?

八時 (はちじ) by itself just means 8 o’clock; whether it’s a.m. or p.m. comes from context.

To be explicit:

午前八時 – 8 a.m.
午後八時 – 8 p.m.

You can use Arabic numerals or kanji:

午前8時 = 午前八時

Other times:

8:30 → 八時半 (はちじはん)
8:15 → 八時十五分 (はちじじゅうごふん)
8:05 → 八時五分 (はちじごふん)

All of these fit the same pattern:

朝礼は午前八時に始まります。 – The morning assembly starts at 8 a.m.
朝礼は八時半に始まります。 – The morning assembly starts at 8:30.

Can I change the word order in this sentence? For example: 八時に朝礼が始まります?

Yes, you can change word order somewhat, as long as particles (は, が, に, を, etc.) stay with the right words. Examples:

朝礼は八時に始まります。
– Topic is 朝礼, neutral schedule statement.
八時に朝礼が始まります。
– Focus on the event that happens at 8: “At 8, the morning assembly starts.”
八時に、朝礼は始まります。
– Still grammatical; slightly emphatic/contrastive feeling depending on context.

In Japanese, particles carry most of the grammatical information, so the word order is more flexible than in English. However, the default, neutral order for your sentence is exactly:

朝礼は八時に始まります。

How do I turn this into a question like “Does the morning assembly start at 8?” or “What time does the morning assembly start?”

You mainly add か at the end (and keep the polite form).

Yes/no question
“Does the morning assembly start at 8?”
- 朝礼は八時に始まりますか。
Possible answers:
- はい、始まります。= Yes, it does.
- いいえ、始まりません。= No, it doesn’t.
Wh-question (what time?)
“What time does the morning assembly start?”
- 朝礼は何時に始まりますか。
  (なんじに)
Answer example:
- 朝礼は八時に始まります。 = “The morning assembly starts at 8.”