Learn Hardcore Swahili: Wanafunzi thelathini wanakaa darasani. - Thirty students are staying in the classroom.

Swahili does not have articles (no “a/an/the”). So wanafunzi thelathini simply means “thirty students,” and context supplies definiteness. If you need to specify “these/those thirty students,” add a demonstrative:

wanafunzi hawa thelathini = these thirty students
wanafunzi wale thelathini = those thirty students

Why does the number come after the noun?

In Swahili, numerals normally follow the noun they count. So “students thirty” is the standard order: wanafunzi thelathini. Only a few quantifiers like “kila” (every) come before the noun.

Should the number agree with the noun class here? Why isn’t it “wathalathini”?

Numbers behave differently:

The numbers 1–5 agree with the noun class: for class 1/2 (people) they are mmoja, wawili, watatu, wanne, watano.
From 6 upward, and multiples of ten (like thelathini = 30), numbers are invariable—no class prefix. So “students thirty” is wanafunzi thelathini, not “wathalathini.”

How would I say “thirty-one students” or “thirty-two students”?

Add the unit after “thelathini,” and for 1–5 use class 2 agreement:

31 students: wanafunzi thelathini na mmoja
32 students: wanafunzi thelathini na wawili (Similarly: …na watatu, …na wanne, …na watano.)

What does the verb form wanakaa tell me exactly? Does it mean “sit” or “are sitting”?

The marker -na- gives present/imperfective aspect, which can be either simple present or present progressive depending on context. So wanakaa can mean “they sit/they stay” or “they are sitting/are staying.” To emphasize a current, ongoing state of being seated, many speakers use the perfect to show a resultant state: wamekaa = “they are seated.”

Why does the verb still have wa- (they) if the subject wanafunzi is already there?

Swahili verbs must carry a subject prefix regardless of whether the subject noun is stated. Here wa- is the 3rd-person plural subject marker (class 2/human plural), matching wanafunzi. So agreement is obligatory: wa- + -na- + kaa → wanakaa.

Could I say wako darasani instead of wanakaa darasani? What’s the difference?

wako darasani = “they are (located) in the classroom.” It just states presence/location.
wanakaa darasani = “they sit/are sitting” or “they stay/are staying” in the classroom (an activity or state of remaining).
wamekaa darasani = “they are seated in the classroom” (resultant state from sitting down).

What does darasani literally mean? Do I need a preposition like “in”?

darasani is darasa (classroom) + the locative suffix -ni, which means “in/at/on.” You don’t need a separate preposition; darasani alone means “in the classroom.”

If I wanted to be more explicit, how would I say “inside the classroom” vs. “in/at the classroom”?

“Inside the classroom”: ndani ya darasa
“In/at the classroom”: darasani or katika darasa (both are fine; darasani is the most natural).

How do I make the sentence negative?

For present tense negation, drop -na-, use the negative subject prefix, and change the final verb -a to -i:

Affirmative: wanafunzi thelathini wanakaa darasani
Negative: wanafunzi thelathini hawakai darasani (= they do not sit/are not sitting in the classroom) If you used location instead:
wako darasani → hawako darasani (= they are not in the classroom)

Can the number come first, like “thelathini wanafunzi”?

Not in the normal “noun + number” construction. However, you can make the number itself the subject: thelathini wako darasani = “Thirty (of them) are in the classroom.” When counting a specific noun directly, keep the number after the noun: wanafunzi thelathini.

Is there a more specific verb for “to sit (down)”?

Yes, keti means “to sit (down)” more specifically. Compare:

wanakaa darasani = they sit/are staying/are seated (context decides)
wanaketi darasani = they are sitting (down) in the classroom
Resultant state: wameketi darasani = they are seated in the classroom

How would I ask “How many students are in the classroom?”

Use the class-2 “how many” word wangapi and either a location verb or kaa:

Wanafunzi wangapi wako darasani? (How many students are in the classroom?)
Wanafunzi wangapi wanakaa darasani? (How many students are sitting/staying in the classroom?)