Learn Hardcore Indonesian: Rapat sekolah diadakan di aula pagi ini. - The school meeting is held in the hall this morning.

“the school meeting” – a meeting that belongs to or is organized by the school (e.g. staff meeting, parents’ meeting).
It does not necessarily mean “a meeting that happens at the school building.” For that, Indonesian would more naturally say rapat di sekolah (a meeting at school).

So:

rapat sekolah → “school meeting” (institution-related)
rapat di sekolah → “meeting at school” (location-related)

What does diadakan mean, and which verb is it from?

Diadakan is the passive form of mengadakan, which means “to hold / to organize (an event).”

Breakdown:

ada = to exist, to be (there is/are)
adakan (ada + -kan) = to make something exist → to put on / to hold (an event)
mengadakan (meN- + adakan) = to hold / to organize (active voice)
- Kami mengadakan rapat. = We hold a meeting.
diadakan (di- + adakan) = to be held (passive voice)
- Rapat diadakan… = The meeting is held… / was held…

In your sentence:

Rapat sekolah diadakan di aula pagi ini.
- Literally: The school meeting is held in the hall this morning.

Why is the sentence passive (diadakan) instead of using an active form?

Indonesian often uses the passive when:

The doer (agent) is obvious or not important.
The event itself is the focus.

Here, the important information is that the school meeting is happening in the hall this morning, not who is organizing it.

Compare:

Active:
Pihak sekolah mengadakan rapat di aula pagi ini.
The school (administration) is holding a meeting in the hall this morning.
Passive (original):
Rapat sekolah diadakan di aula pagi ini.
The school meeting is (being) held in the hall this morning.

Both are correct; the passive just emphasizes the meeting rather than the organizer.

Where is the subject of the sentence? There’s no “they” or “someone”.

In Indonesian, especially with the passive, the agent (doer) is often simply left out.

Rapat sekolah is the grammatical subject.
diadakan is the passive verb.
The agent (e.g. pihak sekolah, guru, kepala sekolah) is implied and omitted.

If you really want to mention who is holding it, you can add oleh:

Rapat sekolah diadakan oleh pihak sekolah di aula pagi ini.
The school meeting is held by the school (administration) in the hall this morning.

But most of the time, oleh + agent is not necessary unless you want to emphasize the doer.

What’s the difference between diadakan and ada, and why can’t we just say ada rapat sekolah?

ada = there is / there are / to exist
- Ada rapat sekolah pagi ini. = There is a school meeting this morning.
diadakan = to be held / to be organized (passive verb)
- Rapat sekolah diadakan di aula pagi ini. = The school meeting is held in the hall this morning.

The difference:

Ada rapat sekolah pagi ini.
Just tells you that a school meeting exists/occurs this morning.
Rapat sekolah diadakan di aula pagi ini.
Adds information that it is being held (organized) and where (in the hall).

You can say Ada rapat sekolah di aula pagi ini, but it’s a bit more neutral and less event-focused than diadakan.

In diadakan and di aula, is di the same word? How do I tell them apart?

They are related but different:

di- (attached, no space) → passive prefix on verbs
- diadakan, dibaca, dilihat
- Always written together with the verb.
di (separate word) → preposition meaning in / at / on
- di aula, di sekolah, di rumah
- Always written separately from the noun.

So in the sentence:

diadakan → is held (passive verb, di- prefix)
di aula → in the hall (di preposition + noun)

Spelling rule:
If di + verb → one word (diadakan, dibuka).
If di + place noun → two words (di rumah, di aula).

Why is the order di aula pagi ini and not pagi ini di aula? Is there a rule for place and time?

Both orders are grammatically correct, but the most common neutral order in Indonesian is:

Place → Time

So:

Rapat sekolah diadakan di aula pagi ini. ✔
Rapat sekolah diadakan pagi ini di aula. ✔ (also fine)

Both mean the same thing. You might change the order to emphasize something:

Pagi ini, rapat sekolah diadakan di aula.
Emphasis on this morning.
Di aula, rapat sekolah diadakan pagi ini.
Emphasis on in the hall.

In everyday speech and writing, “… di aula pagi ini” is very natural.

What exactly does pagi ini mean? Is it “this morning” or “in the morning”?

Pagi ini literally means “this morning”:

pagi = morning
ini = this

It refers specifically to the morning of “today”.

Related expressions:

pagi tadi / tadi pagi = earlier this morning (already finished)
besok pagi = tomorrow morning

So:

Rapat sekolah diadakan di aula pagi ini.
The school meeting is held in the hall this morning.

If you just want to say in the morning in a general or habitual sense, you might simply use pagi without ini:

Rapat biasanya diadakan pagi.
The meeting is usually held in the morning.

How do we know if diadakan is present or past tense here?

Indonesian verbs do not change form for tense. diadakan itself is tense-less; the time is understood from:

time words (like pagi ini) and
context.

Rapat sekolah diadakan di aula pagi ini can be:

The school meeting *is being held in the hall this morning* (if said around that time or as a schedule).
The school meeting *was held in the hall this morning (in some contexts, but usually you’d prefer *tadi pagi or add another time clue).

If you clearly mean future, you might add akan:

Rapat sekolah akan diadakan di aula pagi ini.
The school meeting will be held in the hall this morning. (sounds like a schedule/announcement)

For past and already finished this morning, many speakers would say:

Rapat sekolah diadakan di aula tadi pagi.
The school meeting was held in the hall earlier this morning.

Why is there no “the” or “a” in rapat sekolah and di aula?

Indonesian does not have articles like “a / an / the”. Whether something is definite or indefinite is decided by context, not by a separate word.

So:

Rapat sekolah diadakan di aula pagi ini.

can be translated as:

The school meeting is held in the hall this morning.
or
A school meeting is held in the hall this morning.

In many real contexts (e.g. a notice to staff), English would naturally use “the” because everyone knows which meeting is meant, but Indonesian expresses that through shared context, not grammar:

If both speaker and listener know the meeting → “the” in English.
If it’s just “some meeting” → “a” in English.

Indonesian keeps the same form either way.