Learn Hardcore Malay: Guru ajar murid tentang sejarah di kelas. - The teacher teaches the student about history in class.

So literally: “Teacher teach student about history in class.” Context and extra words (like a, the, the, -s) are added in English but not needed in Malay.

Why is it ajar and not mengajar here? Are both correct?

Both ajar and mengajar mean “to teach,” but:

ajar is the root form and is very common in speech and informal writing.
mengajar is the standard, more formal verb form.

So:

Guru ajar murid… sounds neutral/informal, natural in everyday speech.
Guru mengajar murid… sounds more formal or textbook-like.

Grammatically, both are correct; it’s mainly about formality and style.

Is murid singular or plural here? Does it mean student or students?

Murid by itself is number‑neutral: it can mean student or students, depending on context.
If you want to make it clearly plural, you can say:

murid-murid = students (reduplication often marks plural)
or add a number or quantifier:
tiga murid = three students
para murid = the students (as a group, more formal/literary).

So Guru ajar murid… can be understood as “The teacher teaches the student(s)…” depending on the situation.

Why is there no word for “the” or “a” in the sentence?

Malay does not have definite or indefinite articles like “the” and “a/an”.
Nouns like guru, murid, and kelas are inherently flexible; context decides whether you should translate them as the teacher, a teacher, the student, a student, the class, or a class.
If you really need to emphasize definiteness, you can use other words or context (like itu = that, ini = this), but basic sentences usually omit this.

Can the sentence be translated as “The teacher teaches the students about history in the classroom”?

Yes, that’s a very natural translation.

Guru → the teacher
murid → the students (here understood as plural)
di kelas → in the classroom

Because Malay leaves number and definiteness to context, “The teacher teaches the students about history in the classroom” is a good, natural English rendering.

Is this sentence formal or informal? Would it be okay in writing?

With ajar (instead of mengajar), the sentence sounds neutral to informal, very common in everyday speech.
In more formal writing (school essays, exams, official texts), you’d more often see:

Guru mengajar murid tentang sejarah di dalam kelas.

So your sentence is fine in conversation and informal writing; for formal contexts, swap ajar → mengajar and possibly di kelas → di dalam kelas.

Is tentang necessary? Could I say Guru ajar murid sejarah di kelas without it?

You can hear Guru ajar murid sejarah di kelas in casual speech, and people will understand it.
However, tentang makes the relation clearer: ajar … tentang … = teach … about ….
Without tentang, sejarah is just another object and can sound slightly telegraphic or informal.

For clear, standard Malay, tentang is recommended:

Guru ajar murid tentang sejarah di kelas.

What is the difference between tentang and mengenai? Could I use mengenai here?

Both tentang and mengenai can mean about / regarding.
In your sentence, you can say:

Guru ajar murid tentang sejarah di kelas.
Guru ajar murid mengenai sejarah di kelas.

Both are acceptable.
Tentang is very common and neutral; mengenai can sound a bit more formal or bookish, but the meaning is basically the same here.

What is the difference between di kelas and di dalam kelas?

Both can be translated as “in the class / in the classroom.”
Nuances:

di kelas = at class / in class; short, common, and fully acceptable.
di dalam kelas = literally “inside the class/classroom”; slightly more explicit, often more formal or descriptive.

In many everyday contexts, di kelas and di dalam kelas are interchangeable, and people frequently just say di kelas.

Why is di written separately from kelas, but sometimes di- is attached to verbs like dibaca?

There are two different di in Malay:

di as a preposition of place (location), always written separately:
- di kelas = in/at the class
- di rumah = at home
di- as a prefix marking passive verbs, always attached to the verb:
- dibaca = is/was read
- ditulis = is/was written

In di kelas, di is a preposition, so it must be written separately from kelas.

How do we know the tense? Could it mean “taught” instead of “teaches”?

Malay verbs do not change form for tense.
Ajar can mean teach / teaches / taught / is teaching / was teaching, depending on context.
To specify time, Malay usually adds time expressions:

Guru ajar murid tentang sejarah di kelas semalam. = The teacher taught the students about history in class yesterday.
Guru sedang ajar murid… = The teacher is teaching the students…

Without extra markers, context tells you whether to translate it as present, past, or future.

Is the word order fixed? Could I move di kelas or tentang sejarah?

The basic word order is Subject – Verb – Object – (Other information).
Your sentence follows this:

Guru (subject)
ajar (verb)
murid (object)
tentang sejarah (what they are taught about)
di kelas (location)

You can normally move the di kelas phrase around a bit:

Guru ajar murid tentang sejarah di kelas.
Di kelas, guru ajar murid tentang sejarah. (more emphasis on location)

However, you should keep ajar murid tentang sejarah together; splitting that more aggressively would sound unnatural.

How would I say “The teacher is teaching the students about history in class now” in Malay?

You can add sedang (in the process of) and a time word like sekarang (now):

Guru sedang mengajar murid tentang sejarah di kelas sekarang.

In everyday speech you might also hear:

Guru sedang ajar murid tentang sejarah di kelas sekarang.

Sedang marks an ongoing action, similar to English “is … -ing.”

Can I replace guru and murid with pronouns? How would that look?

Yes. For example:

Dia ajar mereka tentang sejarah di kelas.
- dia = he / she
- mereka = they / them

Or, if the teacher is “we” (inclusive of the listener):

Kami ajar murid tentang sejarah di kelas. = We teach the students about history in class.

The basic word order stays the same: pronoun (subject) + verb + object + other information.