Learn Hardcore Swahili: Ni kalenda hii ndio itatusaidia kupanga ratiba. - It is this calendar that will help us plan the schedule.

It’s a focus/cleft construction. It singles out the focused element (here, kalenda hii “this calendar”) and says “It is X that …”. So the nuance is “It is this calendar (and not something else) that will help us plan the schedule.”

Can I drop either ni or ndio/ndiyo?

You can drop the initial ni and say: Kalenda hii ndiyo itatusaidia kupanga ratiba. (still focused, very common)
You can remove the focus entirely: Kalenda hii itatusaidia kupanga ratiba. (neutral statement, no special emphasis)
You can also express the cleft with a relative: Ni kalenda hii itakayotusaidia kupanga ratiba. or Kalenda hii ndiyo itakayotusaidia kupanga ratiba.

Is ndio the same as ndiyo (“yes”)? Which one should be here?

Ndiyo is the usual spelling for “yes.” In cleft focus, you also get forms like ndiye, ndicho, ndilo, ndivyo, ndizo, ndiyo, which agree with the noun class.
Because kalenda is class 9, the agreeing focus form is traditionally ndiyo: Ni kalenda hii ndiyo itatusaidia …
Many speakers and writers use ndio as a general, non-agreeing focus marker in everyday usage. So your sentence with ndio is widely understood, but in careful/standard writing you’ll often see ndiyo here.

Do these focus markers change with different noun classes?

Yes. A few common ones:

Class 1 (person, singular): ndiye — e.g., Ni mwalimu huyu ndiye atakayekusaidia.
Class 5: ndilo — Gari ndilo tutakalotumia.
Class 7: ndicho — Kitabu ndicho ninachotafuta.
Class 8: ndivyo — Vitabu ndivyo ninavyovitaka.
Class 9 (e.g., kalenda, kalamu): ndiyo — Kalenda ndiyo itatusaidia.
Class 10 (plural of 9): ndizo — Kalenda ndizo zitatusaidia.

Why does the verb start with i- in itatusaidia?

Because the verb agrees with the subject noun class. Kalenda is class 9, whose subject marker is i-. So: i- (SM9) + -ta- (future) + rest of the verb → itatusaidia “it will help us.”

Can you break down itatusaidia?

i- = subject marker (class 9, agreeing with kalenda)
-ta- = future tense
-tu- = object marker “us”
saidia = verb stem “help”
Final vowel -a Whole word: “it will help us.”

I see tu inside the verb. Is that the same tu that means “only”?

No. Here -tu- is the object marker “us,” and it must be inside the verb: i-ta-tu-saidia → itatusaidia. The enclitic tu meaning “only” comes after the verb or phrase, e.g., Itatusaidia tu = “It will only help us.”

Why is it kalenda hii and not hii kalenda?

Standard Swahili usually places the demonstrative after the noun: kalenda hii (“this calendar”). Pre-nominal hii kalenda occurs in speech for emphasis or in some regional styles, but post-nominal is the default in careful writing.

Could I use ambayo instead of this ndio/ndiyo focus?

Yes. A relative clause version is perfectly fine:

Ni kalenda hii ambayo itatusaidia kupanga ratiba. That’s more neutral/formal. The ndiyo cleft is punchier and foregrounds the focus more strongly.

Why isn’t there a relative marker in the clause after ndio/ndiyo (like itakayotusaidia)?

Both patterns are acceptable:

Focus + finite clause: … ndiyo itatusaidia … (very common)
Focus + relative clause: … ndiyo itakayotusaidia … (more explicit structure) The meaning is the same; the second just adds a relative marker.

Is kupanga ratiba the only way to say “to plan a schedule”?

No. Common options:

kupanga ratiba = to plan/arrange a schedule
kuandaa ratiba = to prepare/draw up a schedule Both are natural; pick based on nuance.

Can I use a subjunctive after kusaidia, like “help us (to) plan”?

Yes. Both are idiomatic:

Infinitive: Itatusaidia kupanga ratiba.
Subjunctive: Itatusaidia tupange ratiba. The subjunctive can feel a bit more purposive (“help us so that we plan”).

What exactly does ratiba mean?

Ratiba is a timetable/schedule/agenda (e.g., ratiba ya wiki “weekly schedule,” ratiba ya masomo “class timetable”). It’s class 9; the plural (class 10) is also ratiba, with agreement on the verb or adjectives to show plurality.

How would the sentence look in the plural, “these calendars are the ones that will help us …”?

Ni kalenda hizi ndizo zitatusaidia kupanga ratiba. Changes:
hizi (these; class 10)
ndizo (focus marker for class 10)
zi- subject marker on the verb: zitatusaidia (zi-ta-tu-saidia)