Learn Hardcore Swahili: Mwalimu wetu ni mchapakazi shuleni. - Our teacher is hard-working at school.

Mwalimu – teacher (a person who teaches)
wetu – our (possessive for we/us with this noun class)
ni – is / are (the linking verb “to be”)
mchapakazi – a hardworking person (literally “work-beater,” i.e., someone who really hits/attacks work)
shuleni – at school (literally “in/at the school”; shule = school, -ni = “in/at”)

So the whole sentence is: Our teacher is (a) hardworking (person) at school.

Why do we need ni here? In English I might say “Our teacher is hardworking,” but Swahili sometimes omits “to be,” right?

In standard Swahili, you normally use ni to link a subject to:

a noun: Yeye ni mwalimu – He/She is a teacher
some adjectives or descriptive nouns: Mwalimu wetu ni mchapakazi – Our teacher is hardworking

You can sometimes hear ni dropped informally in speech, but in correct, clear Swahili you keep it in a sentence like this. So:

Mwalimu wetu ni mchapakazi shuleni. – Our teacher is hardworking at school.

Without ni, the sentence would sound incomplete or very colloquial.

What exactly is mchapakazi? Is it an adjective meaning “hardworking,” or a noun?

Mchapakazi is grammatically a noun meaning a hardworking person, but in practice it functions very much like an adjective:

Yeye ni mchapakazi. – He/She is hardworking (a hard worker).
Mwalimu wetu ni mchapakazi. – Our teacher is hardworking.

Structure (roughly):

m- – noun class prefix for “person” (class 1)
chapa – to hit/beat/strike
kazi – work

So the image is “someone who really hits work hard.” It’s an idiomatic, positive word for a person who works hard, not for the work itself.

If you want a more clearly adjective-like phrase you can also hear:

mwenye bidii – diligent, hardworking
anafanya kazi kwa bidii – he/she works hard

But mchapakazi is very common and natural.

What’s the difference between shule and shuleni?

shule = school (basic noun)
shuleni = at school / in school / in the school

The -ni ending is a locative suffix, meaning roughly “in/at/on.” Adding it to a place noun often means “at that place.” Examples:

nyumba – house → nyumbani – at home
kanisa – church → kanisani – at church
soko – market → sokoni – at the market

So:

Mwalimu wetu ni mchapakazi shule. – feels incomplete / odd
Mwalimu wetu ni mchapakazi shuleni. – correct: Our teacher is hardworking at school.

Why is it mwalimu wetu and not mwalimu letu or something else for “our teacher”?

Possessive adjectives in Swahili must agree with the noun class of the word they describe.

Mwalimu is in noun class 1 (people, singular, “m-/m-” class).
The class 1 form of “our” is wetu.

So:

mwalimu wetu – our teacher
rafiki wetu – our friend
mtoto wetu – our child

Compare with class 5 nouns (often starting with ji-/Ø), where “our” is letu:

gari letu – our car
jambo letu – our matter/issue

So mwalimu wetu is correct; mwalimu letu would be ungrammatical.

Where is the subject pronoun “he/she” in this sentence? Why don’t we see something like yeye?

Swahili usually does not use separate subject pronouns (I, you, he, she, etc.) unless you want to emphasize them.

In this sentence, the subject is the noun phrase Mwalimu wetu – our teacher. That is already clear enough, so there’s no need for an extra yeye (he/she).

You could say, with extra emphasis:

Yeye, mwalimu wetu, ni mchapakazi shuleni. – He/She, our teacher, is hardworking at school.

But the normal, neutral way is simply:

Mwalimu wetu ni mchapakazi shuleni.

Swahili only adds yeye, mimi, sisi, etc. when you’re stressing contrast, clarification, or emphasis.

Can I move shuleni in the sentence, like in English “At school, our teacher is hardworking”?

Yes, shuleni is fairly flexible in position. These are all acceptable:

Mwalimu wetu ni mchapakazi shuleni.
Shuleni, mwalimu wetu ni mchapakazi.
Mwalimu wetu shuleni ni mchapakazi. (a bit more marked but possible in context)

The most neutral/common version is what you were given:

Mwalimu wetu ni mchapakazi shuleni.

Putting shuleni first adds a little emphasis to the location, like “At school, our teacher is hardworking (there).”

How would I say “Our teachers are hardworking at school” (plural)?

You need to pluralize both the noun and keep the same ni:

Walimu wetu ni wachapakazi shuleni.

Changes:

Mwalimu (singular, class 1) → Walimu (plural, class 2) – teacher → teachers
mchapakazi (hardworking person, sing.) → wachapakazi (hardworking people, pl.)
- m- (class 1) → wa- (class 2)

So:

Mwalimu wetu ni mchapakazi shuleni. – Our teacher is hardworking at school.
Walimu wetu ni wachapakazi shuleni. – Our teachers are hardworking at school.

Note that ni stays the same; it works for both singular and plural.

If I want to say “Our teacher is very hardworking at school,” how do I add “very”?

Add sana after mchapakazi (or at the end):

Mwalimu wetu ni mchapakazi sana shuleni.
Mwalimu wetu ni mchapakazi shuleni sana. (less common; first version is better)

sana means very / a lot. So:

Yeye ni mchapakazi sana. – He/She is very hardworking.

What’s the difference between “at school” and “in our school” in Swahili?

shuleni – at school / in school (general or context-specific)
shuleni kwetu – at our school (literally “at school at-our-place”)
katika shule yetu – in our school (more literally, with katika = “in/inside”)

So you can say:

Mwalimu wetu ni mchapakazi shuleni. – Our teacher is hardworking at school.
Mwalimu wetu ni mchapakazi shuleni kwetu. – Our teacher is hardworking at our school.

The original sentence usually implies the school context you’re already talking about, so just shuleni is enough.

Is mwalimu used only as a noun, or also as a form of address, like calling someone “Teacher”?

Mwalimu is both:

A common noun:
- Mwalimu wetu ni mchapakazi shuleni. – Our teacher is hardworking at school.
A form of address or title:
- Mwalimu, nina swali. – Teacher, I have a question.

So students can address a teacher simply as Mwalimu, just like English Teacher or Sir/Ma’am in a school setting.

How would I put this in the past and future: “Our teacher was hardworking…” / “Our teacher will be hardworking…”?

You change the form of the verb “to be”:

past “was” – alikua or alikuwa
- Mwalimu wetu alikuwa mchapakazi shuleni. – Our teacher was hardworking at school.
future “will be” – atakua or atakuwa
- Mwalimu wetu atakuwa mchapakazi shuleni. – Our teacher will be hardworking at school.

In present tense (your original sentence), you use ni:

Mwalimu wetu ni mchapakazi shuleni. – Our teacher is hardworking at school.

(Colloquially you’ll see both kua and kuwa spellings; kuwa is the more standard.)

Could I say Mwalimu wetu shuleni ni mchapakazi, or does wetu have to come right after mwalimu?

The most natural placement is to keep the possessive wetu directly after the noun it belongs to:

Mwalimu wetu ni mchapakazi shuleni. ✅

If you say:

Mwalimu wetu shuleni ni mchapakazi.

it is still understandable, but it slightly risks being heard as “Our teacher at school is hardworking” (which might contrast with the same teacher in another context). It’s not wrong, but it changes emphasis and sounds less neutral than the original.

For a learner, it’s best to stick to:

noun + its possessive together: mwalimu wetu
then the rest: ni mchapakazi shuleni.