Learn Hardcore Swahili: Chemsha-bongo ngumu imeandaliwa na mwalimu wetu wa hesabu. - A difficult puzzle has been prepared by our mathematics teacher.

Chemsha-bongo is a fixed compound noun (literally “brain-cooking”). The hyphen shows it’s one unit meaning “brain-teaser” or “mind challenge.” You don’t split it into two separate words.

What part of speech and noun class is Chemsha-bongo, and how does that affect the verb agreement?

Chemsha-bongo is a noun in class 9 (the N–/M– group).
In perfect tense the subject‐agreement prefix for class 9 is i-, so you get imeandaliwa (“it has been prepared”).

Break down the verb imeandaliwa. What tense, aspect, and voice is it?

i-: subject prefix for class 9 (“it”)
-me-: perfect aspect marker (“has…”)
-andaliwa: passive form of andaa (“to prepare”), formed by adding -liwa to the stem
Altogether imeandaliwa = “it has been prepared” (perfect passive).

Why do we use na before mwalimu in na mwalimu wetu wa hesabu?

In Swahili passive sentences the agent (English “by …”) is introduced by na. So na mwalimu wetu literally means “by our teacher.”

How does mwalimu wetu wa hesabu work? Why wetu and not yetu?

mwalimu (“teacher”) is a class 1 noun.
The class 1 possessive “our” is etu, which becomes wetu after the initial m- of mwalimu.
wa hesabu is the genitive connector for class 1, meaning “of mathematics.”
So mwalimu wetu wa hesabu = “our math teacher.”

Why does the adjective ngumu have no prefix, and why does it come after chemsha-bongo?

In Swahili adjectives normally follow the noun they modify.
ngumu (“difficult”) is one of a few invariable adjectives (like nene, nzito, rahisi) that never take agreement prefixes.
Therefore you say chemsha-bongo ngumu, not ngumu chemsha-bongo or ___gumu chemsha-bongo.

Why is it wa hesabu and not ya hesabu to mean “of mathematics”?

The genitive connector agrees with the class of the head noun:

mwalimu is class 1 → connector wa
If the head were class 9/10 (e.g. nyumba), you’d use ya
Hence mwalimu wa hesabu = “teacher of math.”

Can you swap wetu and wa hesabu (i.e. say mwalimu wa hesabu wetu)?

No. Possessive pronouns attach immediately after the noun (mwalimu wetu), while the specialization phrase (wa hesabu) follows afterward. Swapping them would confuse which element is possessed and which describes the field.

What’s the difference between andaa, tayarisha, and weka tayari when you want to say “prepare”?

andaa = “to prepare” (general, cover tasks or materials)
tayarisha = causative of tayari (“ready”), literally “make ready”
weka tayari = “put in a ready state,” often used for setting up equipment or arranging tables
In the context of puzzles, andaa is the most natural choice, hence imeandaliwa.