Learn Hardcore Indonesian: Karena airnya dangkal, anak-anak bermain dengan aman sambil belajar mengukur kedalaman. - Because the water is shallow, the children play safely while learning to measure the depth.

“the water” (definite) – referring to specific water that both speaker and listener know about (e.g., the water in this pool/river).
“its water / the water there” – often implies “the water at that place/situation”.

In this sentence, airnya is best understood as “the water (there)” or “that water”, not simply water in general.

If you said karena air dangkal, it would sound more like a general statement, “because water is shallow,” which is odd. -nya makes it clear we’re talking about specific water in context.

Why is anak-anak repeated? Is that just a plural? Can I just say anak?

Yes, anak-anak is the common way to say “children”.

anak = child
anak-anak = children

Reduplication (repeating the word) is a common way to make plurals in Indonesian, especially for people, animals, and some objects.

You can see anak used in the plural sense if the context is clear, but:

anak-anak explicitly means “children” (more natural here).
anak alone would usually be understood as “a child” or “the child” in this sentence.

Why is it bermain, not just main? What’s the difference?

Both appear in real Indonesian, but they differ in register:

bermain = to play (standard, more formal/neutral)
main = to play (very common in conversation, more informal/colloquial)

In a written, neutral sentence like this, bermain is more appropriate and complete grammatically.

Spoken:

Formal/neutral: Anak-anak bermain di sungai.
Informal: Anak-anak main di sungai.

Both are correct in speech; bermain just sounds more standard.

Why is it dengan aman and not just aman after bermain?

Indonesian often uses dengan + adjective to form an adverbial meaning “in a … way”:

aman = safe (adjective)
dengan aman = safely (literally “with safe(ness)”)

So:

bermain aman is possible in casual speech but can sound a bit incomplete/less natural in careful writing.
bermain dengan aman clearly means “play safely” (play in a safe way).

Other examples:

berbicara dengan jelas = to speak clearly
mengemudi dengan hati-hati = to drive carefully

What does sambil mean exactly? How is it different from sementara or ketika?

sambil means “while” with the nuance of doing two actions at the same time by the same subject.

In the sentence:

anak-anak = subject of both actions
bermain and belajar mengukur kedalaman = actions done simultaneously

So sambil is perfect here:
“the children play safely while (they are also) learning to measure the depth.”

Comparison:

sambil – same subject, two concurrent activities
- Dia makan sambil menonton TV. (He eats while watching TV.)
sementara – “while/whereas”; often contrasts two different subjects or situations
- Saya bekerja, sementara dia tidur. (I work, while he sleeps.)
ketika / saat – “when”; focuses on time, not necessarily simultaneous ongoing actions
- Ketika saya tiba, dia sudah pergi. (When I arrived, he had already left.)

Here, sementara and ketika would sound off; sambil is the natural choice.

Why is there no untuk (to) before mengukur? Could I say belajar untuk mengukur kedalaman?

Both are possible, but slightly different in feel.

In Indonesian, belajar + verb is very common:

belajar mengukur kedalaman = to learn to measure the depth

Adding untuk is not wrong:

belajar untuk mengukur kedalaman

…but in this type of sentence it can sound a bit more formal or wordy. In everyday and neutral usage, belajar + verb (without untuk) is more natural.

So:

belajar mengukur kedalaman – preferred, smooth, standard
belajar untuk mengukur kedalaman – acceptable, more formal/emphatic

What is the role of mengukur here? Is it a noun or a verb?

mengukur is a verb, the active form meaning “to measure”.

Structure:

belajar = to learn
mengukur = to measure
kedalaman = depth

So belajar mengukur kedalaman = “(they) learn to measure the depth.”

Indonesian allows a verb to directly follow belajar in this way, instead of needing an infinitive marker like English “to” or French “à/de”.

What does kedalaman literally mean? How is it related to dalam?

kedalaman is formed from:

dalam = deep / inside
ke- … -an = a common prefix–suffix pair that turns adjectives into abstract nouns or “-ness” words.

So:

dalam → kedalaman = “depth”

Roughly:

dalam = deep
kedalaman = deepness / depth (the level or measure of how deep something is)

Other examples:

tinggi (tall/high) → ketinggian (height)
panas (hot) → kepanasan (heat / overheated)

Could we say mengukur dalamnya air instead of mengukur kedalaman? Would that mean the same thing?

Yes, you can, but the structure and nuance change a bit.

mengukur kedalaman
- Literally: “measure (the) depth”
- General and abstract: depth as a measurable quantity.
mengukur dalamnya air
- Literally: “measure how deep the water is” / “measure the water’s depth”
- dalamnya = “its depth / how deep it is” (from dalam + -nya)

Both would be understood as measuring how deep the water is.
mengukur kedalaman is slightly more neutral and textbook-like.
mengukur dalamnya air feels a bit more descriptive/colloquial: focusing on “how deep the water is”.

Can the word order be changed, for example: Anak-anak bermain dengan aman sambil belajar mengukur kedalaman karena airnya dangkal?

Yes, that sentence is grammatically correct.

Original: Karena airnya dangkal, anak-anak bermain dengan aman sambil belajar mengukur kedalaman.
- Emphasis: the reason comes first. “Because the water is shallow, (therefore) the children can play…”
Variant: Anak-anak bermain dengan aman sambil belajar mengukur kedalaman karena airnya dangkal.
- Emphasis: what the children do, and then you mention the reason afterward.

Both are natural. Indonesian is quite flexible with clause order, as long as the relationships (like karena = because) are clear.

Is the comma after Karena airnya dangkal required?

In standard written Indonesian, it is normal and recommended to put a comma after a dependent clause that comes first:

Karena airnya dangkal, anak-anak bermain …
Kalau hujan, kita tidak jadi pergi.
Jika sempat, saya akan datang.

So yes, the comma is expected here.
In very informal writing (text messages, chats), people sometimes drop it, but in proper writing you should include it.