In aula nessuno parla quando entra la professoressa.

In aula is a very common school-related expression in Italian, meaning in the classroom. In this kind of set phrase, Italian often leaves out the article.

Both forms can exist, but they are not used in exactly the same way:

• in aula = in class / in the classroom, as a general setting
• nell'aula = in the specific classroom

So In aula nessuno parla... sounds natural as a general statement about classroom behavior.

Because nessuno comes before the verb, and in that position it already makes the sentence negative.

• Nessuno parla = nobody speaks
• Non parla nessuno = nobody speaks

Both are correct, but the rule is:

• nessuno before the verb → no non
• nessuno after the verb → use non

So in this sentence, nessuno parla is perfectly correct.

Because nessuno is grammatically singular in Italian, even though in English nobody refers to many possible people.

So Italian uses:

• nessuno parla = nobody speaks

not:

• nessuno parlano

This is the same idea as English nobody speaks, not nobody speak.

Both are possible, but the word order changes the feel slightly.

• quando entra la professoressa = when the teacher comes in
• quando la professoressa entra = when the teacher comes in

In Italian, putting the verb before the subject is very common, especially with verbs of movement or appearance like:

• entrare
• arrivare
• uscire

So entra la professoressa sounds very natural. It can feel a bit like the teacher comes in / in comes the teacher.

In Italian, professore/professoressa is often used for a teacher, especially in middle school, high school, and sometimes beyond. It does not always mean a university professor in the English sense.

So in this sentence, la professoressa most naturally means the female teacher.

If the teacher were male, it would be:

• il professore

Italian usually uses the definite article with nouns like this when referring to a specific person or role.

So:

• entra la professoressa = the teacher comes in

Without the article, it would sound incomplete or unnatural in standard Italian.

Italian uses articles more often than English does, so this is something learners notice a lot.

Italian often uses the present tense to talk about things that happen regularly, generally, or habitually.

This sentence describes a general classroom rule or repeated situation:

• In aula nessuno parla quando entra la professoressa.

So the present tense works like English present simple in:

• Nobody talks when the teacher comes in.

It is not necessarily describing one single event; it can describe what normally happens.

Quando means when and introduces a time clause.

Here it connects the two parts:

• nessuno parla = nobody speaks
• quando entra la professoressa = when the teacher comes in

So it tells us at what moment nobody speaks.

It is a very common way to link actions in Italian.

Yes, that is also grammatical.

Compare:

• Nessuno parla = nobody speaks
• Non parla nessuno = nobody speaks

The meaning is basically the same, but the emphasis is a little different.

• nessuno parla puts the negative subject first
• non parla nessuno can sound a bit more emphatic or stylistically different

In your sentence, nessuno parla is straightforward and very natural.

Italian often puts a place expression first to set the scene.

So:

• In aula nessuno parla... = In the classroom, nobody speaks...

This word order highlights the setting first. Italian is generally more flexible than English with word order, as long as the sentence remains clear.

You could also say:

• Nessuno parla in aula quando entra la professoressa

but the original version sounds very natural because it starts with the context.

Usually it is understood as when the teacher comes in or when the teacher enters, meaning the moment or occasion of her entering.

If you wanted to stress an action happening while she is in the process of entering, Italian would more often use a different structure, such as one with mentre in the right context.

So in this sentence, quando is best understood as a time trigger: at the moment the teacher enters, nobody speaks.

Usually yes, or at least a specific teacher understood from the context.

The article la in la professoressa suggests a definite, identifiable person:

• the teacher

Depending on context, it could mean:

• the usual teacher of that class
• a specific female teacher everyone knows
• the teacher being talked about in the conversation

So even if English sometimes says just teacher, Italian often prefers la professoressa here.