Tredecim discipuli in bibliotheca tacent, dum magistra verba nova in tabula scribit.

Because tredecim (thirteen) is an indeclinable numeral in Latin. That means it does not change its ending for case, gender, or number.

So in tredecim discipuli, the noun discipuli changes as needed, but tredecim stays the same.

• tredecim discipuli = thirteen students
• tredecim discipulos = thirteen students (as a direct object)
• tredecim discipulorum = of thirteen students

The numeral stays tredecim each time.

Discipuli is nominative plural, and here it is the subject of tacent.

A quick breakdown:

• singular: discipulus = student
• plural nominative: discipuli = students
• plural accusative: discipulos = students (when they are the direct object)

Since the students are the ones being silent, they must be in the nominative:

• Tredecim discipuli tacent = Thirteen students are silent.

The ending -nt tells you the verb is third person plural in the present tense.

So:

• taceo = I am silent / I keep quiet
• taces = you are silent
• tacet = he/she/it is silent
• tacent = they are silent

Because the subject is tredecim discipuli (thirteen students), the verb has to be plural:

• discipuli tacent = the students are silent

It can mean either, depending on context.

The verb is taceo, tacere, which means:

• to be silent
• to keep quiet
• sometimes to say nothing

In this sentence, tacent naturally means something like:

• are silent
• keep quiet

Latin often uses a verb where English might use an adjective:

• Latin: discipuli tacent
• English: the students are silent

Because in with the ablative usually means in or on in a location sense: where?

Here, bibliotheca is in the ablative singular:

• nominative: bibliotheca
• ablative: bibliotheca

For first-declension nouns, the nominative singular and ablative singular often look the same, so the form does not visibly change here.

So:

• in bibliotheca = in the library

This is different from in + accusative, which usually means into or onto and shows motion toward a place.

A very common rule is:

• in + ablative = in / on = location, rest
• in + accusative = into / onto = motion toward

So:

• in bibliotheca = in the library
• in tabula = on the board / on the tablet
• in bibliothecam = into the library

In your sentence, nobody is moving into anything. The phrase tells you where the students are and where the teacher is writing, so the ablative is used.

Dum here means while.

It introduces a clause describing something happening at the same time:

• Tredecim discipuli in bibliotheca tacent, dum magistra ... scribit.
• The students are silent while the teacher writes ...

So the sentence gives two simultaneous actions:

1. the students are being quiet
2. the teacher is writing

Because scribit goes with magistra, not with discipuli.

The sentence has two different clauses:

1. Tredecim discipuli in bibliotheca tacent

   • subject: discipuli
   • verb: tacent (plural)

2. dum magistra verba nova in tabula scribit

   • subject: magistra
   • verb: scribit (singular)

So the number of the verb depends on its own subject, not on the nearest noun in the sentence.

Because magistra is the feminine form, meaning female teacher.

• magister = male teacher
• magistra = female teacher

Since the sentence uses magistra, the writer is specifically referring to a woman teacher.

Because verba is a neuter plural noun, so the adjective must match it.

The noun is:

• singular: verbum = word
• plural: verba = words

Since verba is:

• neuter
• plural
• accusative here (direct object of scribit)

the adjective novus, nova, novum must also be:

• neuter
• plural
• accusative

That form is nova.

So:

• verba nova = new words

This is a very important Latin pattern: neuter plural nominative and accusative often end in -a.

Because scribit is a transitive verb here: the teacher writes something.

What does she write?
verba nova

That makes verba nova the direct object, so it is in the accusative.

With neuter second-declension nouns like verbum, the accusative plural is:

• verba

And the matching adjective is also neuter plural accusative:

• nova

So:

• magistra verba nova scribit = the teacher writes new words

Yes. Tabula originally means something like board, plank, tablet, or a writing surface. In a classroom sentence like this, it is naturally understood as on the board.

So in tabula scribit means she writes:

• on the board
• or literally, on/in the writing surface

Latin words often cover a range of meanings depending on context. Here the classroom context makes board the most natural interpretation.

Because Latin in with the ablative can cover location in a broader way than English in sometimes does. Depending on the noun, it may be best translated as:

• in
• on
• occasionally at

So:

• in bibliotheca = in the library
• in tabula = on the board

English chooses the most natural preposition, but Latin still uses in.

Latin has a freer word order than English because noun endings show what each word is doing.

English depends heavily on word order:

• The teacher writes the words is different from
• The words write the teacher

Latin is clearer because of endings:

• magistra is nominative, so it is the subject
• verba nova is accusative, so it is the object
• scribit is the verb

That means Latin can move words around for style, emphasis, or rhythm without changing the basic meaning.

This sentence is actually fairly straightforward, but it still does not have to match English word order exactly.

Yes. That would also be good Latin.

Because Latin endings show grammatical function, several word orders are possible, for example:

• dum magistra verba nova in tabula scribit
• dum magistra in tabula verba nova scribit
• dum in tabula magistra verba nova scribit

These may sound slightly different in emphasis, but the basic meaning stays the same.

Yes. Bibliotheca comes from Greek and means library or a place for books.

A learner may notice that it looks similar to English words like:

• bibliography
• bibliophile
• bibliotheque-type words in some modern languages

That resemblance can help with vocabulary memory.

Because the sentence describes two actions happening at the same time in the present scene:

• tacent = they are silent
• scribit = she writes / is writing

In simple Latin narrative or classroom sentences, the present tense often works the way English simple present or present progressive does, depending on context.

So the sentence can feel like:

• the students are being quiet
• while the teacher is writing

Grammatically, discipuli is masculine plural. In many Latin texts, a masculine plural can refer to:

• a group of males
• or a mixed group

If the writer wanted to refer specifically to a group of female students, you would expect discipulae.

So in isolation, discipuli is masculine in form, but depending on context it may or may not imply an all-male group.

Not especially from a grammar standpoint. The comma is mainly a matter of punctuation and readability.

The important Latin grammar point is that dum introduces a subordinate clause:

• main clause: Tredecim discipuli in bibliotheca tacent
• subordinate clause: dum magistra verba nova in tabula scribit

Whether a modern editor prints a comma can vary, but the grammar remains the same.