Asilimia ndogo ya wanafunzi wetu huchelewa darasani.

Because ya is the connector meaning of, and it agrees with the head noun asilimia.

So the structure is:

• asilimia ndogo = a small percentage
• ya wanafunzi wetu = of our students

A key point: the connector agrees with asilimia, not with wanafunzi. That is why it is ya, not wa.

Because wetu must agree with wanafunzi.

• mwanafunzi = student
• wanafunzi = students

Wanafunzi is a plural noun in the wa-/m-wa noun class, so the possessive our becomes wetu.

So:

• wanafunzi wetu = our students

If the noun belonged to a different noun class, the form of our would change.

Huchelewa uses the hu- form, which usually expresses a habitual or general action.

So huchelewa means something like:

• are usually late
• tend to be late
• are late as a general pattern

It is not mainly describing one specific event happening right now. It gives a general statement.

In standard Swahili, the habitual marker hu- is commonly used without the usual subject marker.

Compare the idea:

• huchelewa = is/are usually late

So even though the subject is asilimia ndogo ya wanafunzi wetu, the verb can simply appear as huchelewa.

This is normal for the habitual form and often surprises English speakers, because English always needs an expressed subject in the verb phrase.

Darasani comes from darasa plus the locative ending -ni.

• darasa = class / classroom
• darasani = in class / in the classroom / to class

The ending -ni often adds a location meaning. In this sentence, darasani is best understood as in class or to class, depending on the English translation style.

Ndogo means small or little. Here it modifies asilimia:

• asilimia ndogo = a small percentage

The adjective agrees with the noun class of asilimia. With this noun, the form ndogo is the correct one.

So the phrase is describing the percentage as small, not the students.

Here, asilimia is the head noun of the subject phrase, and it is treated as a single amount or proportion:

• asilimia ndogo ya wanafunzi wetu = a small percentage of our students

Even though wanafunzi is plural, the main noun of the whole phrase is asilimia. That is why words linked directly to the head noun, such as ya, are determined by asilimia.

The sentence breaks down like this:

• Asilimia ndogo = a small percentage
• ya wanafunzi wetu = of our students
• huchelewa = are usually late / tend to be late
• darasani = in class / to class

So the pattern is:

[subject noun phrase] + [habitual verb] + [location]

That makes the sentence a very natural general statement.

It is about a general habit or usual situation, not one specific day.

That is because of huchelewa. If you wanted to talk about a particular occasion, Swahili would usually use a different tense or aspect.

So this sentence means that, in general, only a small percentage of the students are late.

The singular is mwanafunzi.

So:

• mwanafunzi = student
• wanafunzi = students

This is a common noun-class pattern in Swahili:

• singular m-
• plural wa-

That same plural class is why our becomes wetu in wanafunzi wetu.