Learn Hardcore Malay: Guru memperkenalkan moderator muda itu kepada pelajar di dewan. - The teacher introduces that young moderator to the students in the hall.

Guru = subject (the one doing the introducing) → the teacher
memperkenalkan = verb → introduces
moderator muda itu = direct object (the one being introduced) → that young moderator
kepada pelajar = indirect object (who receives the introduction) → to the students
di dewan = place → in/at the hall

So the meaning in terms of roles is:

The teacher introduced that young moderator to the students in the hall.

It does not mean the moderator introduced the teacher; that would need a different structure, e.g.:

Moderator muda itu memperkenalkan guru kepada pelajar di dewan.
→ The young moderator introduced the teacher to the students in the hall.

Why do we say kepada pelajar and not just pelajar after the object?

In Malay, when you mark an indirect object (the person to whom something is done/given), you usually use kepada (“to”):

Saya memberi buku kepada Ali.
I give a book to Ali.
Dia memperkenalkan saya kepada bosnya.
He/She introduced me to his/her boss.

So in:

…memperkenalkan moderator muda itu kepada pelajar…

kepada pelajar means “to the students”.
You cannot simply drop kepada here; pelajar without kepada would sound like another direct object rather than “to the students”.

Why is pelajar not marked explicitly as plural? How do I know it means “students”?

In Malay, nouns are usually not marked for plural. Pelajar by itself can mean:

a student or
students

Context tells you which is intended. Here:

a teacher
introducing a moderator
in a hall (di dewan, a big space)

This context strongly suggests there is a group, so pelajar is understood as “students”.

If you really want to stress the plurality, you have options:

para pelajar = the students (formal, collective)
pelajar-pelajar = students (reduplication; can emphasize plurality)

E.g.:

Guru memperkenalkan moderator muda itu kepada para pelajar di dewan.

Why is itu placed after moderator muda, instead of before like in English (“that young moderator”)?

Malay word order for this kind of phrase is:

Noun + Adjective + Demonstrative (ini/itu)

So:

moderator = noun
muda = adjective “young”
itu = “that”

Combined: moderator muda itu = “that young moderator”.

You cannot put itu before the noun like English “itu moderator” for this meaning. Post-nominal placement is the normal pattern:

buku baru itu = that new book
kereta merah itu = that red car

Can I omit itu? How would the meaning change?

Yes, you can omit itu:

Guru memperkenalkan moderator muda kepada pelajar di dewan.

Without itu, moderator muda is less specific. In English this is closer to:

“a young moderator” rather than “that young moderator”.

So:

With itu → moderator muda itu = that particular young moderator (already known/identified in context)
Without itu → moderator muda = a/young moderator in a more general or newly introduced sense.

Why is it di dewan and not ke dewan?

di = at / in / on (location, no movement implied)
ke = to / towards (motion, direction)

In this sentence, di dewan describes where the introduction takes place:

di dewan = in/at the hall

We are not talking about moving to the hall, so ke dewan would be wrong here.
You’d use ke dewan for movement:

Kami berjalan ke dewan.
We walk to the hall.

Can I say di dalam dewan instead of di dewan? Is there a difference?

Both are possible:

di dewan = at/in the hall (neutral, very common)
di dalam dewan = inside the hall (more explicitly “inside”)

di dalam emphasizes the interior of the place but in many everyday contexts the difference is small. In this sentence, both are grammatically fine:

Guru memperkenalkan moderator muda itu kepada pelajar di dalam dewan.
The teacher introduced that young moderator to the students inside the hall.

Is guru gender-specific? How do I say “male teacher” or “female teacher” if needed?

Guru is gender-neutral in Malay. It just means teacher, regardless of gender.

If context requires you to show gender, you can add a descriptor:

guru lelaki = male teacher
guru perempuan / guru wanita = female teacher

But normally, guru alone is enough, just like “teacher” in English when gender is not important.

How would I turn this into a yes–no question like “Did the teacher introduce the young moderator to the students in the hall?”

Several natural options:

Formal / clear question marker
- Adakah guru memperkenalkan moderator muda itu kepada pelajar di dewan?
  → Did the teacher introduce that young moderator to the students in the hall?
Colloquial, using intonation (common in speech)
- Guru memperkenalkan moderator muda itu kepada pelajar di dewan?
  Same wording as the statement, but with rising intonation.
Using “sudah” to emphasize completion
- Adakah guru sudah memperkenalkan moderator muda itu kepada pelajar di dewan?
  → Has the teacher already introduced that young moderator to the students in the hall?

All are grammatical; choice depends on formality and nuance.

What is the difference between memperkenalkan and memperkenalkan diri?

memperkenalkan (someone/something) = to introduce (someone/something)
You need an object:
- Guru memperkenalkan moderator muda itu…
  The teacher introduced that young moderator…
memperkenalkan diri = to introduce oneself (reflexive)
- Moderator muda itu memperkenalkan diri kepada pelajar di dewan.
  The young moderator introduced himself/herself to the students in the hall.

In your original sentence, because the teacher is introducing someone else, you cannot use memperkenalkan diri there.

Why is there no word for “the” before pelajar and dewan? How is “the” expressed in Malay?

Malay does not have direct equivalents to the English articles “the” and “a/an”.

Definiteness is usually shown by:

Context
Demonstratives like ini (this) and itu (that)
Sometimes para (for groups), possessives, etc.

In the sentence:

pelajar ≈ “(the) students”
dewan ≈ “(the) hall”

Both are understood as specific from context (it’s the known students and the known hall in that situation).
You only see an explicit “that” with moderator muda itu. For the others, Malay simply leaves them bare and relies on context.