Nikifanya mazoezi ya chemia, dada yangu ananisaidia kuelewa majaribio ya fizikia.

Nikifanya is made of several parts:

• ni- = I (1st person singular subject marker)
• -ki- = a special marker meaning when / while / whenever
• -fanya = do
• -a = final vowel of the verb

So Nikifanya mazoezi ya chemia literally means “When I do chemistry exercises / While I’m doing chemistry exercises.”

The -ki- form usually introduces a dependent clause of time or condition: when/whenever/while (I) do…

Both can mean “when I do”, but there are small differences:

• Nikifanya

  • Uses the -ki- marker.
  • Very common in spoken and written Swahili.
  • Often sounds slightly more informal/natural in everyday speech.

• Ninapofanya

  • Built from nina- (I do / I am doing) + -po- (time/place marker) + fanya.
  • Also means “when I do / whenever I do.”
  • Can sound a bit more formal or explicit.

In most everyday contexts, Nikifanya and Ninapofanya are interchangeable in meaning here.

It can mean either, depending on context:

• Habitual/general:
  Nikifanya mazoezi ya chemia, dada yangu ananisaidia…
  → Whenever / whenever I’m working on chemistry exercises, my sister helps me…

• Specific / current time:
  In the right context it can also mean:
  → (Right now) while I’m doing chemistry exercises, my sister is helping me…

On its own, the sentence is often understood as habitual (“whenever / when(ever) I do…”).

The comma is serving the same role as in English:

• Nikifanya mazoezi ya chemia,
  = “When I do chemistry exercises,” (dependent clause)

• dada yangu ananisaidia kuelewa majaribio ya fizikia.
  = “my sister helps me understand physics experiments.” (main clause)

In Swahili writing, it’s normal and good style to separate a subordinate clause (introduced by forms like -ki-, -po-, ikiwa, etc.) from the main clause with a comma, just like in English.

ananisaidia breaks down like this:

• a- = he/she (3rd person singular subject)
• -na- = present tense marker (“is / does”)
• -ni- = me (1st person singular object marker)
• saidia = help (verb root)
• -a = final vowel

So ananisaidia is literally “she/he is helping me” or “she/he helps me.”

In the sentence, because dada yangu (my sister) is the subject, we know a- refers to “my sister.”

• kuelewa = ku- (infinitive marker) + elewa (understand) → “to understand”
• kunielewa = ku- (infinitive) + ni- (object “me”) + elewa → “to understand me”

In this sentence, the sister is not helping to understand me, she is helping me to understand something else (the physics experiments).

So:

• ananisaidia kuelewa majaribio ya fizikia
  = “she helps me to understand the physics experiments”

If you said ananisaidia kunielewa, it would mean “she helps (someone) to understand me,” which is a different meaning.

This is about noun class agreement.

• zoezi (exercise) → class 5
• mazoezi (exercises) → class 6

For class 5/6 nouns, the possessive/genitive agreement is:

• la / ya (not za)

Examples:

• zoezi la chemia = a chemistry exercise
• mazoezi ya chemia = chemistry exercises
• jaribio la fizikia = a physics experiment
• majaribio ya fizikia = physics experiments

So ya is correct with mazoezi and majaribio.
za would go with a different noun class (e.g. class 10, like shule za msingi — primary schools).

The same noun class rule as above applies:

• jaribio (experiment) → class 5
• majaribio (experiments) → class 6
• For class 5/6 plurals, we use ya.

So:

• majaribio ya fizikia = experiments of physics / physics experiments

You cannot change ya here; it has to agree with majaribio’s noun class.
You could change the noun, for example:

• michunguzi ya fizikia (investigations of physics) – but the agreement would change with the noun class.

Yes, that word order is grammatically correct:

• Dada yangu ananisaidia kuelewa majaribio ya fizikia nikifanya mazoezi ya chemia.

Swahili word order is flexible. You can put the “when/while” clause at the beginning or at the end:

• Nikifanya mazoezi ya chemia, dada yangu ananisaidia…
• Dada yangu ananisaidia… nikifanya mazoezi ya chemia.

Both mean essentially the same thing.
Placing Nikifanya… first slightly emphasizes the condition/time (“When I do chemistry exercises…”).

Yes, these are common standard terms:

• chemia = chemistry
• fizikia = physics

You may also see spelling variants like kemia or fiziki, especially in older texts or in certain regions, but chemia and fizikia are widely used and understood in modern Standard Swahili.

So:

• mazoezi ya chemia = chemistry exercises
• majaribio ya fizikia = physics experiments

dada yangu simply means “my sister” and does not say whether she is older or younger.

If you need to be more specific, Swahili often uses:

• dada yangu mkubwa = my older/big sister
• dada yangu mdogo = my younger/little sister

But in this sentence, dada yangu alone just tells you it’s a female sibling, without age information.

Yes, jaribio / majaribio is flexible in meaning. It can mean:

• experiment(s) (scientific)
• test(s) or trial(s)
• attempt(s)

In this context—paired with fizikia (physics)—“experiments” is the most natural translation:
majaribio ya fizikia → physics experiments.

You could also say:

• mazoezi ya fizikia = physics exercises (practice questions)
• majaribio ya chemia = chemistry experiments

So the mix “chemistry exercises” vs “physics experiments” is a stylistic choice, not a grammatical requirement.