Learn Hardcore Indonesian: Dalam kelas, guru menjelaskan kelebihan dan kekurangan belajar sendiri di rumah. - In class, the teacher explains the advantages and disadvantages of studying alone at home.

Di kelas = in class / in the classroom (neutral, very common in speech).
Dalam kelas = inside the class / within the class, slightly more formal or bookish.

In this sentence, Dalam kelas, guru menjelaskan… sounds like written or semi‑formal Indonesian, as if describing what happened during the class session.
You could also say:

Di kelas, guru menjelaskan…
Guru menjelaskan … di kelas.

All are acceptable; the meaning is essentially the same here.

Could I say Di dalam kelas instead of Dalam kelas? Is there any difference?

Yes, you can say Di dalam kelas:

Di dalam kelas, guru menjelaskan…

Nuance:

Di kelas: simple location marker (in class / in the classroom).
Dalam kelas: slightly more formal; can refer to the situation within the class as an event.
Di dalam kelas: literally inside the classroom, emphasizing being physically inside a space.

In most everyday contexts, di kelas is perfectly natural and most common.
Dalam kelas and di dalam kelas fit better in written or more formal narration.

Why is it just guru and not seorang guru or gurunya? How do I know if it’s the teacher, a teacher, or the teacher(s)?

Indonesian doesn’t mark definiteness (the/a) or number (singular/plural) the way English does. The bare noun guru can mean:

a teacher
the teacher
teachers (in some contexts)

In this sentence, context usually makes you interpret it as the teacher of that class.

To be more specific, you can say:

seorang guru = a teacher (one teacher, non‑specific)
gurunya = the teacher (with a sense of that/this teacher, often known to speaker and listener)
para guru / guru-guru = teachers (plural)

Examples:

Seorang guru menjelaskan kelebihan dan kekurangan…
→ A teacher explained the advantages and disadvantages…
Gurunya menjelaskan kelebihan dan kekurangan…
→ The teacher (that we know) explained the advantages and disadvantages…

What is the structure and meaning of menjelaskan?

Menjelaskan is formed from:

root: jelas = clear
prefix: meN-
suffix: -kan

So menjelaskan literally means to make something clear, i.e. to explain.

Grammar:

menjelaskan is a transitive verb: it normally takes a direct object (what is explained).

In the sentence:

guru menjelaskan kelebihan dan kekurangan belajar sendiri di rumah.
- guru = subject
- menjelaskan = verb
- kelebihan dan kekurangan belajar sendiri di rumah = object (the thing being explained)

Example with an explicit recipient:

Guru menjelaskan kelebihan dan kekurangan belajar sendiri di rumah kepada murid-murid.
→ The teacher explained the pros and cons of studying alone at home to the students.

Should there be a tentang (about) after menjelaskan?
Like: menjelaskan tentang kelebihan dan kekurangan…?

You can say menjelaskan tentang…, but it is usually unnecessary and often avoided in careful/formal writing.

Guru menjelaskan kelebihan dan kekurangan…
→ already means The teacher explained the advantages and disadvantages…
Guru menjelaskan tentang kelebihan dan kekurangan…
→ literally explained about the advantages and disadvantages…

Because menjelaskan already includes the idea of about, adding tentang is somewhat redundant. In spoken Indonesian it’s common and acceptable; in more formal style, menjelaskan + object (without tentang) is preferred.

What exactly do kelebihan and kekurangan mean? Are they always advantages and disadvantages?

They are a very common pair:

kelebihan
- form: lebih (more) + ke- -an → kelebihan
- meanings:
  - advantage, strength, plus point
  - excess, surplus (in other contexts)
kekurangan
- form: kurang (less) + ke- -an → kekurangan
- meanings:
  - disadvantage, weakness, minus point
  - lack, shortage (in other contexts)

As a set phrase:

kelebihan dan kekurangan ≈ pros and cons, advantages and disadvantages, strengths and weaknesses.

Examples:

Apa kelebihan dan kekurangan metode ini?
→ What are the pros and cons of this method?

Is belajar sendiri the same as belajar sendirian? What’s the difference?

They are related but not identical in nuance:

belajar sendiri
- Focus: doing it by yourself, without help/assistance.
- Emphasizes independence.
belajar sendirian
- Focus: doing it alone, without other people present.
- Emphasizes being alone/without company.

So:

Saya belajar sendiri di rumah.
→ I study by myself at home (no teacher helping; may still chat with friends online, etc.).
Saya belajar sendirian di rumah.
→ I study alone at home (no one else around).

In many everyday cases, they overlap and people may use either, but this nuance exists.
In the original sentence, belajar sendiri di rumah highlights independent study at home.

Does di rumah describe belajar or sendiri?
Could the sentence mean in one’s own house?

In kelebihan dan kekurangan belajar sendiri di rumah:

belajar sendiri = studying by oneself
di rumah = at home, modifying the verb phrase belajar sendiri.

So the phrase means:

the advantages and disadvantages of studying by oneself at home.

If you want to say in one’s own house, you move sendiri:

belajar di rumah sendiri
→ to study in one’s own house/home (emphasis: it’s your own home, not somewhere else)

Compare:

belajar sendiri di rumah
→ studying by yourself at home.
belajar di rumah sendiri
→ studying at your own house.

Why is it di rumah and not just rumah? When do I need di?

Di is the basic preposition for location: at / in / on.

rumah = a house / home (the noun itself).
di rumah = at home / in the house.

In this sentence, you need di because rumah is used as a place where the action happens:

belajar di rumah = to study at home.

Without di, rumah would not be clearly a location in the sentence; it would just be a bare noun next to the verb, which does not work here.

How would I say at his/her home instead of just at home?

Use the possessive suffix -nya:

di rumahnya = at his house / at her house / at their house (context decides which).

So you could say:

Dalam kelas, guru menjelaskan kelebihan dan kekurangan belajar sendiri di rumahnya.
→ In class, the teacher explained the pros and cons of studying alone at his/her home.

Note the difference:

di rumah = at home (general, speaker’s or generic).
di rumahnya = at his/her/their home (third person).

How do we know this happened in the past? Menjelaskan on its own doesn’t show tense, right?

Correct. Indonesian verbs generally do not change form for tense like English does.
Menjelaskan can mean:

explains (present)
is explaining (present continuous)
explained (past)

The time is understood from:

Context, or
Time expressions (e.g. tadi, kemarin, besok, etc.).

If you want to make the past tense explicit, you can add a time marker:

Tadi dalam kelas, guru menjelaskan…
→ Earlier in class, the teacher explained…
Kemarin di kelas, guru menjelaskan…
→ Yesterday in class, the teacher explained…

Can guru here also mean teachers (plural)? How do I make it clearly plural?

Yes, guru by itself can be singular or plural, depending on context.
If you specifically want teachers (plural), you can say:

para guru
guru-guru (reduplication)

Examples:

Para guru menjelaskan kelebihan dan kekurangan belajar sendiri di rumah.
→ The teachers explained the pros and cons of studying alone at home.
Guru-guru menjelaskan…
→ also plural, more casual in tone.

In the original sentence with just guru, most readers will assume a single teacher unless the wider context says otherwise.

What’s the difference between belajar and mempelajari? Could I say mempelajari sendiri di rumah?

Both relate to learning/studying, but their usage differs:

belajar
- intransitive: no direct object is required.
- means to study / to learn in general.
- Ex: Saya belajar di rumah. – I study at home.
mempelajari
- transitive: takes a direct object (what you study).
- means to study something in depth / to learn about something.
- Ex: Saya mempelajari bahasa Indonesia. – I study Indonesian.

So you would say:

kelebihan dan kekurangan belajar sendiri di rumah
→ the pros and cons of studying by yourself at home (general).

You could say:

kelebihan dan kekurangan mempelajari bahasa Indonesia sendiri di rumah
→ the pros and cons of studying Indonesian by yourself at home.

But you wouldn’t normally say just mempelajari sendiri di rumah without an object; that would sound incomplete.

Is this sentence formal, informal, or neutral? Could I use it in writing, speech, or both?

The sentence is neutral to slightly formal, and works well in:

written Indonesian (essays, reports, textbooks), and
spoken Indonesian in a school/academic context.

Features that lean a bit formal:

Dalam kelas at the beginning sounds more like narrative or written style;
in everyday speech, many people might more naturally say:
- Di kelas tadi, guru jelasin… (colloquial, note jelasin instead of menjelaskan).

So the original is perfectly suitable for:

compositions,
exam questions,
formal explanations,
or polite speech.