Learn Hardcore Swahili: Mazoea mabaya ya kuchelewa darasani yote yanapaswa kubadilishwa. - All bad habits of being late to class should be changed.

Mazoea is in noun class 6 (ma-), which is normally plural.
There isn’t a commonly used everyday singular like zoea meaning one habit; people usually talk about mazoea as a set or state (like English habits or habitual behavior).

So in this sentence, mazoea means something like bad habits / bad habitual behavior (specifically about being late).

Why is it mabaya and not mbaya after mazoea?

Mbaya is the base adjective meaning bad. In Swahili, adjectives agree with the noun class of the noun they describe. For class 6 nouns (ma- class, like mazoea), mbaya takes the ma- agreement:

Class 6 (ma-) + -baya → mabaya

Some examples:

mafunzi mabaya – bad trainings
matokeo mabaya – bad results
mazoea mabaya – bad habits

So mabaya is just mbaya modified to match the class 6 noun mazoea.

What is the role of ya in mazoea mabaya ya kuchelewa darasani?

Ya here is the genitive connector (like of) that links a noun to something that describes it:

mazoea mabaya – bad habits
ya kuchelewa darasani – of being late to class

Because mazoea is class 6 (ma-), its genitive connector is ya:

Class 6 (ma-) → ya

So the structure is:

mazoea mabaya (bad habits)
ya (of)
kuchelewa darasani (being late in class)

Literally: bad habits of being late in class.

Is kuchelewa a verb or a noun in this sentence?

Morphologically, kuchelewa is the infinitive (or verbal noun) form of the verb -chelewa (to be late).

In this sentence, it behaves like a noun:

ya kuchelewa = of being late

In Swahili, infinitives with ku- often function like English -ing forms:

kula – to eat / eating
kusoma – to read / reading
kuchelewa – to be late / being late

So here kuchelewa = being late, acting as the thing the habits are about.

What is the difference between darasa and darasani?

darasa = class / classroom / lesson (basic noun form)
darasani = in class / in the classroom / during the lesson

-ni is a locative suffix, often meaning in / at / on. So:

nyumba – house
nyumbani – at home
shule – school
shuleni – at school
darasa – class
darasani – in class / in the classroom

In this sentence, darasani tells you where the lateness happens: being late to/in class.

Why is it yote and not zote, vyote, or something else?

Yote is the form of the adjective -ote (all / the whole / every) that agrees with a class 6 (ma-) noun.

Some forms of -ote for singular/plural:

Class 1/2: mtu yote / watu wote
Class 3/4: mti wote / miti yote
Class 5/6: jambo lote / mambo yote
Class 7/8: kitu chote / vitu vyote
Class 9/10: kazi yote / kazi zote

Mazoea is class 6 → it takes yote:

mazoea yote – all the habits

So yote here means all (of them) and matches mazoea.

Why does the verb start with ya- in yanapaswa?

The ya- at the beginning of yanapaswa is the subject agreement prefix for class 6 (ma-) nouns.

Subject prefixes:

Class 6 (ma-) → ya-
- mazoea yanapaswa – habits should / must
- matokeo yamebadilika – the results have changed

Because mazoea is the subject and it is class 6, the verb uses ya-:

Mazoea … yanapaswa … – the habits … should …

If the subject were singular class 9, for example, you might see inapaswa instead:

tabia mbaya inapaswa kubadilishwa – a bad habit should be changed

What does -paswa mean, and how strong is it (like should or must)?

-paswa is basically the passive form of -pasa, which means something like to be necessary / required.

Yanapaswa literally: they are required / they are supposed (to).
Functionally, it often corresponds to:

should, ought to, or a softer must.

So:

Mazoea … yanapaswa kubadilishwa.
≈ The bad habits … should be changed / ought to be changed.

The strength depends on context and tone:

In formal or moral statements, yanapaswa can feel close to must.
In more neutral advice, it feels like should / ought to.

Why is it kubadilishwa (passive) and not kubadili or kubadilika?

All three are related but differ in voice and transitivity:

-badili – to change something (active, transitive)
- Wanafunzi wanapaswa kubadili mazoea yao.
  – The students should change their habits.
-badilika – to change (by itself) (intransitive)
- Mazoea yanapaswa kubadilika.
  – The habits should change (on their own).
-badilishwa – to be changed (passive)
- Mazoea yanapaswa kubadilishwa.
  – The habits should be changed (by someone).

In your sentence, kubadilishwa emphasizes an outside agent (people, the students, teachers, etc.) needing to change those habits, even though that agent is not mentioned explicitly.

Where can yote go in this noun phrase, and does the position change the meaning?

You may see -ote (like yote) in a few positions with complex noun phrases:

After the main noun (common, neutral):
- mazoea yote mabaya ya kuchelewa darasani
  – all the bad habits of being late to class
After the adjective:
- mazoea mabaya yote ya kuchelewa darasani
  – all those bad habits of being late to class
After the whole descriptive phrase (as in your sentence):
- Mazoea mabaya ya kuchelewa darasani yote yanapaswa kubadilishwa.

Putting yote after the whole descriptive chunk (…ya kuchelewa darasani) tends to emphasize all of that whole set:

[Mazoea mabaya ya kuchelewa darasani] yote – all such bad habits of being late to class.

The core meaning all the bad habits of being late to class stays the same; the difference is mostly in nuance and emphasis, not in basic meaning.

Could I use tabia instead of mazoea? What would change?

Yes, you could say something like:

Tabia mbaya za kuchelewa darasani zote zinapaswa kubadilishwa.

Differences:

tabia – behavior, manners, character traits, habit(s)
mazoea – habits, customs, the things you’re used to doing

Nuance:

tabia mbaya often focuses on moral/behavioral qualities (bad behavior).
mazoea mabaya highlights repeated actions / patterns (bad habits).

Both could fit; mazoea mabaya leans slightly more toward habitual patterns of lateness.

Why is it ya kuchelewa instead of something like ya kuchelewa kwa darasani?

You don’t need kwa here because darasani already has the -ni locative, which gives the meaning in/at class.

The structure is:

kuchelewa – to be late
darasani – in class
kuchelewa darasani – being late in class / to class

If you added kwa, it would be odd and unnecessary here. You use kwa more for other kinds of complements (cause, instrument, manner, etc.), not for a simple location that already has -ni.

Is yanapaswa kubadilishwa the only way to say “should be changed”?

No, there are several natural alternatives, each with a slightly different flavor:

yanatakiwa kubadilishwa – are required / are supposed to be changed
yanatakiwa yabadilishwe – should be changed (subjunctive)
yanapaswa yabadilishwe – should be changed (subjunctive form of the verb)
yanapaswa kubadilika – should change (on their own, no explicit agent)
inashauriwa yabadilishwe – it is advised that they be changed

Your original yanapaswa kubadilishwa is very standard and neutral: they should be changed.

Does kuchelewa always mean to be late, or can it mean other things?

In regular modern Swahili, -chelewa mainly means:

to be late, to be delayed, to take too long.

Typical uses:

Nimechelewa darasani. – I’m late to class.
Gari limechelewa kufika. – The bus has arrived late.
Usichelewe. – Don’t be late.

There are no significantly different everyday meanings you need to worry about; in your sentence it is the normal being late (to class) sense.