Cum magistra intrat, omnes tacent.

Cum can mean two different things:

• with when it is a preposition:
  
  • cum magistra = with the teacher
• when when it is a conjunction introducing a clause:
  
  • cum magistra intrat = when the teacher enters

In this sentence, cum is followed by a full clause (magistra intrat), so it means when, not with.

Because magistra is the subject of intrat.

• magistra = the teacher
• intrat = enters

So magistra intrat literally means the teacher enters.
Subjects of finite verbs normally go in the nominative case, so magistra is nominative singular.

Because magistram would be accusative singular, which is usually used for a direct object, not a subject.

Compare:

• magistra intrat = the teacher enters
  
  • magistra is the subject
• puella magistram videt = the girl sees the teacher
  
  • magistram is the object of videt

Since the teacher is the one doing the entering, Latin uses magistra, not magistram.

Intrat is:

• 3rd person singular
• present tense
• active voice
• from the verb intrare = to enter

So intrat means he/she/it enters or sometimes is entering, depending on context.

Here it refers to magistra, so it means the teacher enters.

Tacent is:

• 3rd person plural
• present tense
• active voice
• from tacere = to be silent, to keep quiet

So tacent means they are silent, they keep quiet, or they fall silent, depending on context.

Because the subject is omnes = everyone/all, the plural verb tacent is used.

Latin omnes literally means all or all people, so it is grammatically plural.

That is why the verb is also plural:

• omnes tacent = all are silent / everyone is silent

English often treats everyone as grammatically singular, but Latin here is thinking in terms of all the people, so it uses the plural.

Omnes is the nominative plural form of omnis, meaning all or every.

In this sentence it is being used on its own, without a noun stated, so it means something like:

• all
• all of them
• everyone

This is very common in Latin: an adjective can stand by itself when the noun is understood.

So omnes tacent literally means all are silent, with people/students understood.

Yes, the present tense here can describe a habitual or repeated action:

• Cum magistra intrat, omnes tacent.
• When the teacher enters, everyone falls silent.

This does not have to mean only one specific moment. It can mean whenever the teacher enters, this is what happens.

Latin often uses the simple present in this way, just as English does in sentences like:

• When the bell rings, the students leave.

Yes, Latin word order is much more flexible than English word order because the endings show the grammar.

This sentence is arranged very naturally:

• Cum magistra intrat = subordinate clause first
• omnes tacent = main clause after it

But other orders are possible, for example:

• Omnes tacent cum magistra intrat.
• Cum intrat magistra, omnes tacent.

These still mean basically the same thing. The chosen order simply presents the when-clause first, then the result.

Yes. Cum magistra intrat is a subordinate clause, and omnes tacent is the main clause.

You can think of the structure like this:

• Cum magistra intrat = when the teacher enters
• omnes tacent = everyone is silent

So the whole sentence means:
When the teacher enters, everyone is silent.

Yes, but not in this straightforward sentence.

Here, intrat is indicative, which is normal for a simple temporal meaning: when the teacher enters.

Latin also has other kinds of cum clauses, especially in more advanced texts, where cum can take the subjunctive, for example in causal or circumstantial senses. But in this sentence, the meaning is simple and direct, so the indicative is exactly what you would expect.

A simple classroom-style pronunciation would be:

• Cum = koom
• magistra = mah-GIS-trah
• intrat = IN-traht
• omnes = OM-ness
• tacent = TAH-kent

In a more classical pronunciation:

• c is always hard, like k
• g is always hard, as in go
• tacent begins with ta-, not tay-

So the sentence sounds roughly like:

koom mah-GIS-trah IN-traht, OM-ness TAH-kent

It can suggest either, depending on context.

The basic meaning of tacent is are silent or keep quiet. But in a sentence like this, English often translates it more naturally as:

• everyone falls silent
• everyone becomes quiet

That is because the action happens in response to the teacher entering. Latin itself just uses the simple verb tacent, and the exact nuance comes from the context.