Learn Hardcore Indonesian: Adik saya mengantuk di kelas, jadi guru menyarankan dia membawa kamus cetak saja daripada membuka ponsel. - My younger sibling is sleepy in class, so the teacher suggests she just bring a printed dictionary rather than open her phone.

Grammatically, it behaves like an adjective in many contexts, but it can also function as a stative verb (“is sleepy”). For learners, you can think of it roughly as “sleepy / feeling sleepy”.

Examples:

Saya mengantuk. = I’m sleepy.
Dia mulai mengantuk. = He/She is starting to feel sleepy.

Ngantuk:

is the colloquial / informal spoken form
you’ll often hear Aku ngantuk in everyday speech
in more formal or written Indonesian, mengantuk is preferred.

So in this sentence, mengantuk di kelas = (was) sleepy in class.

What does di kelas mean, and how is it different from dalam kelas?

di kelas literally = in class or in the classroom (location or situation)
dalam kelas literally = inside the class / inside the classroom

In practice:

di kelas is more common and neutral when talking about what happens in class:
- Dia mengantuk di kelas. = He/She is sleepy in class.
dalam kelas emphasizes the inside-ness (more physical/technical or formal):
- Jangan makan dalam kelas. = Don’t eat inside the classroom.

In your sentence, di kelas is the natural choice. Mengantuk dalam kelas would sound odd or too literal/physical.

How is jadi used here? Is it like “so” in English? Could we use another word?

Yes, jadi here functions like so / therefore as a conjunction showing result:

Adik saya mengantuk di kelas, jadi guru menyarankan…
My younger sibling was sleepy in class, so the teacher suggested…

Other similar connectors:

sehingga – therefore, so (more formal/written)
makanya – that’s why (more informal, spoken)
oleh karena itu – therefore (quite formal)

You could say:

…mengantuk di kelas, sehingga guru menyarankan… (more formal)
…mengantuk di kelas, makanya guru menyarankan… (colloquial)

Jadi is a good neutral choice here.

How does the verb menyarankan work in this sentence? What is its pattern?

Menyarankan = to suggest / to recommend.

The common pattern is:

menyarankan [something]
menyarankan [that someone do something]

In this sentence:

guru = the teacher (subject)
menyarankan = suggested
dia membawa kamus cetak saja = that he/she just bring a printed dictionary (the thing suggested)

So structurally:

guru (subject) + menyarankan (verb) + dia membawa kamus cetak saja (clause as the content of the suggestion)

You can think of it as:
The teacher suggested [that] he/she bring only a printed dictionary.

Why is there no untuk before membawa? Can we say menyarankan dia untuk membawa…?

Both are possible:

guru menyarankan dia membawa kamus cetak saja…
guru menyarankan dia untuk membawa kamus cetak saja…

Meaning is essentially the same: the teacher suggested that he/she (should) bring…

Notes:

Without untuk (version 1) is slightly more concise and very natural.
With untuk (version 2) is also correct and common in speech and writing.

So untuk here is optional. It functions like “to” in “suggest (for him) to bring…”.

What does kamus cetak mean, and why is cetak after kamus?

kamus = dictionary
cetak = printed / print (from the verb mencetak, to print)

So kamus cetak = printed dictionary (a physical, paper dictionary).

In Indonesian, descriptive words usually come after the noun:

kamus cetak = printed dictionary
buku tebal = thick book
guru baru = new teacher

So we say kamus cetak, not cetak kamus.

What is the function of saja in kamus cetak saja? Where can saja appear in a sentence?

Saja here means only / just.

kamus cetak saja = just a printed dictionary / only a printed dictionary

Saja usually comes after the word or phrase it limits:

dia saja = only him/her
melihat saja = just look (don’t do more)
bawa satu buku saja = bring just one book

In your sentence, saja comes after kamus cetak to say:

not other things, just a printed dictionary.

If you put saja elsewhere, the meaning can shift or sound unnatural, e.g.

saja membawa kamus cetak – sounds wrong in this context.

How does daripada membuka ponsel work? Is daripada always used with a verb like this?

Daripada here means rather than / instead of and introduces a comparison or alternative.

Pattern:

[do A] saja daripada [do B]
= just do A rather than do B

So:

membawa kamus cetak saja = just bring a printed dictionary
daripada membuka ponsel = instead of opening/using the phone

You can use daripada with:

verbs: daripada tidur, lebih baik belajar. = rather than sleeping, better to study.
nouns: Saya pilih teh daripada kopi. = I choose tea rather than coffee.

In this sentence it links two actions: membawa (bring) vs membuka (open/use).

Why does membuka ponsel mean “using the phone”? Isn’t it literally “open the phone”?

Literally:

membuka = to open
ponsel = cellphone / mobile phone

But in context, membuka ponsel is commonly understood as:

unlocking/turning on/activating and using the phone, especially opening apps, messages, browser, etc.

Similar everyday expressions:

membuka WhatsApp / membuka Instagram = open WhatsApp / open Instagram
membuka laptop = open (and start using) the laptop

More explicit alternatives that also work here:

menggunakan ponsel = to use the phone
memakai ponsel = to use the phone
main ponsel / main HP (informal) = play with / be on the phone

So daripada membuka ponsel = rather than using/opening the phone.

Why do we use dia for “he/she”? Can it be omitted or replaced with something else?

Dia is the standard third-person singular pronoun: he / she (gender-neutral).

In guru menyarankan dia membawa kamus…:

dia marks who is supposed to bring the dictionary: he/she (my younger sibling).

Alternatives:

Omit the pronoun and say:
- guru menyarankan supaya membawa kamus cetak saja…
  (the subject is understood from context: “(my sibling) should bring…”)
Use beliau instead of dia only if referring to a respected person (teacher, older person, etc.). Here we’re talking about the younger sibling, so dia is appropriate.

Indonesian often drops pronouns when context is clear, but including dia here makes the sentence explicit and clear for learners.

Is the whole sentence formal or informal? Would people say this in everyday conversation, or would they change some words like ponsel?

The sentence is in neutral–slightly formal standard Indonesian:

adik saya – neutral
mengantuk di kelas – neutral
jadi – neutral connector
guru menyarankan – a bit formal/standard
kamus cetak – standard
ponsel – more formal/standard than HP

In everyday casual speech, you might hear something like:

Adik aku ngantuk di kelas, jadi gurunya nyaranin dia bawa kamus cetak aja daripada buka HP.

Changes:

aku instead of saya
ngantuk instead of mengantuk
gurunya (the teacher) vs guru
nyaranin instead of menyarankan (colloquial)
aja instead of saja
HP instead of ponsel

The original sentence is good for textbooks and neutral writing or polite speech.