Juma alifanya kosa katika tahajia, lakini baada ya kusoma dondoo zake tena, aliandika jibu sahihi.

alifanya comes from the verb -fanya (to do / to make).

It breaks down like this:

• a- = he / she
• -li- = past tense
• -fanya = do, make

So alifanya means he/she did or, in this context, he made.

In the sentence, Juma alifanya kosa literally means Juma did/made a mistake, which is the normal Swahili way to say Juma made a mistake.

Swahili often expresses ideas like this with a general verb plus a noun.

So:

• kufanya = to do / to make
• kosa = mistake / error

Together, kufanya kosa means to make a mistake.

This is similar to English expressions like:

• make a decision
• take a look
• have a rest

Even if English sometimes uses a more specific verb, Swahili may prefer a verb+noun combination.

They refer to two different things:

• kosa = mistake / error
• tahajia = spelling / orthography

So kosa katika tahajia means a mistake in spelling or a spelling mistake.

You can think of it as:

• kosa = the problem
• tahajia = the area where the problem happened

katika means in / within / in the matter of.

So kosa katika tahajia literally means a mistake in spelling.

Yes, other forms are possible in some contexts, such as:

• kosa la tahajia = a spelling mistake
• kosa katika tahajia = a mistake in spelling

The version with katika emphasizes the area or field where the mistake occurred. The version with la is often a more compact noun phrase.

lakini means but / however.

It connects the two parts of the sentence:

1. Juma made a spelling mistake.
2. After reading his notes again, he wrote the correct answer.

So it marks contrast: first there was an error, but then he corrected things.

baada ya means after.

It is followed by the infinitive form of a verb:

• kusoma = to read

So:

• baada ya kusoma = after reading / after he read

This is a very common pattern in Swahili:

• baada ya kula = after eating
• baada ya kufika = after arriving
• baada ya kuona = after seeing

The ku- form is the infinitive, and after baada ya, it often translates naturally into English as after + -ing.

dondoo means notes, extracts, or jottings, depending on context. Here it means notes.

zake means his / her, and it agrees with the noun class of dondoo.

So:

• dondoo zake = his notes / her notes

Even though Juma is male, the form zake is not chosen because Juma is male; it is chosen because it must agree with dondoo grammatically.

This is an important Swahili feature: possessives usually agree with the possessed noun, not with the owner's gender.

tena means again.

So:

• kusoma dondoo zake tena = to read his notes again

It comes after dondoo zake, which is very natural in Swahili.

Compare:

• alisoma tena = he read again
• alisoma dondoo zake tena = he read his notes again

In this sentence, tena tells us that Juma went back and reread his notes.

aliandika comes from -andika (to write).

It breaks down as:

• a- = he/she
• -li- = past tense
• -andika = write

So aliandika means he/she wrote.

Notice that both alifanya and aliandika use the same subject marker and tense marker:

• a- = he/she
• -li- = past

That is why both verbs clearly refer to Juma in the past.

Because the subject is already built into the verb.

In Swahili, verbs usually include a subject marker:

• ni- = I
• u- = you
• a- = he/she
• tu- = we
• m- = you all
• wa- = they

So aliandika already means he/she wrote.

Since Juma was already mentioned, Swahili does not need a separate word for he. The verb itself carries that information.

In Swahili, adjectives usually come after the noun they describe.

So:

• jibu = answer
• sahihi = correct

That gives:

• jibu sahihi = correct answer

This noun + adjective order is normal in Swahili:

• mtoto mdogo = small child
• kitabu kizuri = good book
• jibu sahihi = correct answer

Also, the adjective often agrees with the noun class, though some adjectives like sahihi may appear in a more fixed form.

Because the sentence describes two completed actions in sequence:

1. Juma alifanya kosa = Juma made a mistake.
2. aliandika jibu sahihi = he wrote the correct answer.

The phrase baada ya kusoma dondoo zake tena sits between them and explains what happened before the second action.

So the timeline is:

• he made a spelling mistake
• he reread his notes
• he wrote the correct answer

Swahili often uses the simple past (-li-) for completed actions like these.

Yes, it is natural and clear. But Swahili often allows more than one natural phrasing.

For example, you could also hear:

• Juma alifanya kosa la tahajia, lakini baada ya kusoma tena dondoo zake, aliandika jibu sahihi.
• Juma alikosea tahajia, lakini baada ya kusoma tena dondoo zake, aliandika jibu sahihi.

These are slightly different in style:

• alifanya kosa katika tahajia = made a mistake in spelling
• alifanya kosa la tahajia = made a spelling mistake
• alikosea tahajia = misspelled / made a spelling error

The original sentence is perfectly understandable and grammatical; these are just common alternatives.