Walimu wamekuwa wakitumia simu janja kufundisha darasa la mtandaoni.

wamekuwa wakitumia is a compound tense/aspect:

• wa- = they (subject prefix for class 2 / people)
• me-kuwa = have been (perfect of kuwa – to be)
• wa-kitumia = they-using (progressive form of kutumia)

So wamekuwa wakitumia ≈ have been using in English, emphasizing an action that started before now and has been ongoing.

Comparison:

• wanatumia = they are using / they use (present, general or ongoing now)
• walitumia = they used (completed action in the past)
• wamekuwa wakitumia = they have been using (ongoing from the past up to now, or up to some reference time)

It adds a sense of continuity or duration that wanatumia and walitumia don’t clearly express by themselves.

In Swahili, each verb in a complex verb phrase normally takes its own subject agreement marker:

• walimu = teachers
• wa-me-kuwa = they-have-been
• wa-kitum-ia = they-using

So:

• First verb: wamekuwa → must agree with walimu, so it gets wa-
• Second verb: wakitumia → also must agree with walimu, so it gets wa- again

This is standard Swahili structure. Even if verbs are “linked” conceptually (have been using), each finite or quasi-finite verb carries subject agreement.

wakitumia is the progressive / continuous form:

• wa- = they
• -ki- = progressive marker (“while doing, in the process of doing”)
• -tumia = use

The sequence wamekuwa wakitumia literally feels like:

• wamekuwa = they have been
• wakitumia = (while) using

Using wanatumia here (wamekuwa wanatumia) is not normal; the standard pattern for this “have been doing X” idea is wamekuwa wakifanya X (with -ki-). So wamekuwa wakitumia is the expected form.

• mwalimu = teacher (singular, class 1)
• walimu = teachers (plural, class 2)

To say A / the teacher has been using a smartphone to teach an online class, you’d change the verb agreement to singular:

• Mwalimu amekuwa akitumia simu janja kufundisha darasa la mtandaoni.

Changes:

• a-me-kuwa instead of wa-me-kuwa
• a-kitumia instead of wa-kitumia

Everything else stays the same.

Yes. kufundisha is the infinitive (or “verb noun”) of fundisha (to teach).

In this sentence kufundisha expresses purpose:

• …wakitoa simu janja kufundisha… = using a smartphone to teach

So:

• kufundisha = to teach / for teaching
• It’s the normal form after verbs like kutumia when you want to say “use X to do Y”.

simu janja is a fixed compound meaning smartphone (“clever phone”):

• simu = phone
• janja (from mjanja) = clever/smart

This behaves more like a set phrase or a noun–noun compound than a regular noun + “of” + adjective structure, so Swahili doesn’t normally insert ya here.

Saying simu ya janja would sound unusual or wrong. You will most often see:

• simu janja = smartphone
  Sometimes you may also see simu mahiri in more formal or technical language, but simu janja is very common.

darasa la mtandaoni literally means class of online / online class:

• darasa = class (noun class 5)
• la = “of” for class 5 singular nouns
• mtandaoni = online / on the internet

Possessive/“of” agreement:

• Class 1: wa (rafiki wa mtoto)
• Class 5: la (darasa la Kiswahili)
• Class 9: ya (simu ya mkononi), etc.

Since darasa is class 5, you must use la, so:

• darasa la mtandaoni = online class
  darasa ya mtandaoni or darasa wa mtandaoni would be incorrect.

mtandaoni comes from:

• mtandao = network, internet
• -ni = locative suffix (“in/on/at”)

So:

• mtandao = (the) internet
• mtandaoni = on the internet → “online”

You’ll see -ni used similarly in other words:

• nyumba → nyumbani = at home
• shule → shuleni = at school

So darasa la mtandaoni = a class that takes place on the internet.

Swahili doesn’t have articles like a/an/the, so walimu by itself is neutral:

• walimu can be:
  • teachers
  • the teachers
  • some teachers

The exact interpretation depends on context or what has been mentioned earlier.

If you really need to specify:

• walimu fulani = certain/some teachers
• wale walimu = those teachers (more definite)
• walimu wote = all (the) teachers

But in most everyday sentences, context is enough.

This sentence is neutral and perfectly acceptable in both spoken and written Swahili.

• Vocabulary like simu janja and darasa la mtandaoni fits modern, everyday use.
• The tense wamekuwa wakitumia is also normal and natural in news, reports, and conversation.

You could use this sentence in:

• a news report,
• a school article,
• everyday conversation,
• a presentation about online learning.