Öğretmen konuşunca sınıf sustu.

Konuşunca is a subordinating verb form meaning when speaking / when someone spoke / once someone started speaking, depending on context.

In this sentence, öğretmen konuşunca means something like when the teacher spoke or when the teacher started speaking.

It connects the first event to the second one:

• first: the teacher spoke
• then: the class became quiet

It comes from the verb konuşmak = to speak.

Breakdown:

• konuş- = verb stem
• -unca = a suffix meaning when / once / upon

So:

• konuşmak → konuşunca

This suffix changes by vowel harmony, so you can also see:

• -ınca
• -ince
• -unca
• -ünce

For example:

• gelince = when he/she comes
• bakınca = when he/she looks
• okuyunca = when he/she reads

Because of vowel harmony.

The last vowel in konuş- is u, so the suffix takes the matching form -unca.

Compare:

• gel- → gelince
• al- → alınca
• gör- → görünce
• konuş- → konuşunca

So the suffix stays the same in function, but its vowels change to fit the word naturally.

It often means when, but it can also carry a nuance of once or as soon as, depending on context.

In Öğretmen konuşunca sınıf sustu, many learners will naturally feel a slight sense of:

• When the teacher spoke, the class fell silent or
• As soon as the teacher spoke, the class fell silent

So it is mainly temporal, not just a plain dictionary when every time.

Turkish has no articles like the or a/an.

So:

• öğretmen can mean teacher, the teacher, or sometimes a teacher
• sınıf can mean class, the class, or sometimes a class

You understand definiteness from context.

In this sentence, English usually translates them as:

• the teacher
• the class

because the situation sounds specific.

Sustu comes from susmak, which means to become quiet, to fall silent, or to stop talking.

So sustu is not just a static idea like was quiet. It usually describes a change:

• the class was making noise or talking
• then it went quiet

That is why English translations like fell silent or became quiet are often better than just was silent.

It comes from:

• susmak = to become silent
• verb stem: sus-
• past tense suffix: -tu

So:

• sus- + -tu = sustu

The past tense suffix appears as -dı / -di / -du / -dü or -tı / -ti / -tu / -tü, depending on vowel harmony and consonant voicing.

Because sus ends in the voiceless consonant s, the suffix becomes -tu, not -du.

Because sınıf is the subject of the main verb sustu.

In this sentence:

• öğretmen konuşunca = subordinate clause
• sınıf sustu = main clause

Inside the main clause, sınıf is the thing that became quiet, so it is the subject and stays in the basic form.

If it were a direct object, you might expect another form, but here it is not an object.

Turkish often puts the time clause first and the main action after it.

So the structure is:

• Öğretmen konuşunca = when the teacher spoke
• sınıf sustu = the class fell silent

This is very natural in Turkish.

Also, Turkish usually places the main finite verb at the end of its clause, so sustu comes last.

English can do something similar:

• When the teacher spoke, the class fell silent.

So the overall order is actually quite parallel to English here.

Yes. You could say:

• Öğretmen konuştuğunda sınıf sustu.

That also means when the teacher spoke.

The difference is subtle:

• konuşunca often feels a bit more like when / once / as soon as
• konuştuğunda can feel a little more neutral or explicit as when

In many everyday contexts, both are possible and very close in meaning.

Yes, it functions as a subordinate clause.

Turkish often uses non-finite verb forms instead of separate words like English when, after, because, and so on.

So instead of saying something literally like:

• when the teacher spoke

Turkish can build that meaning directly into the verb:

• öğretmen konuşunca

This is a very common Turkish pattern.

A comma is often helpful in writing:

• Öğretmen konuşunca, sınıf sustu.

But Turkish punctuation is sometimes a little less strict than English in such cases, and you may also see it without a comma:

• Öğretmen konuşunca sınıf sustu.

Both are understandable. The version with the comma makes the clause boundary clearer.

Sometimes yes, if the context already makes the subject clear.

For example:

• Konuşunca sınıf sustu.

But that would usually mean When he/she spoke, the class fell silent, and the subject would have to be understood from context.

Including öğretmen makes the sentence clear and specific:

• it was the teacher speaking that caused the class to go quiet.