“‘In’ praepositio est; interdum accusativum habet, interdum ablativum, ut iam scitis,” dicit magistra.

Because the speaker is talking about the word itself, not using it normally in a sentence.

Compare:

• In Roma habitat = here in is being used as a preposition.
• In praepositio est = here in is being mentioned as a vocabulary item.

In English we do the same thing when we say something like in is a preposition. The quotation marks in the Latin sentence are just editorial punctuation to show that clearly.

Latin word order is much freer than English word order. Both praepositio est and est praepositio can mean is a preposition.

Here, praepositio comes first because the sentence is defining in:

• In — topic being discussed
• praepositio est — what it is

So the order feels a bit like: As for in, it is a preposition.

Latin often places words in the order the speaker finds most natural or emphatic, not in a fixed English-style pattern.

Praepositio is the Latin grammatical term for preposition.

It comes from the idea of something placed before another word:

• prae- = before
• positio = placing

That fits prepositions well, because they are placed before the noun or pronoun they govern, as in in urbe or in urbem.

They are objects of habet.

The verb habet literally means has, so the sentence says that in has or takes:

• accusativum
• ablativum

In grammatical English, we usually say a preposition takes or governs a case.

These words refer to case names:

• accusativum = the accusative
• ablativum = the ablative

So the accusative form makes sense because they are the direct objects of habet.

Literally, yes. But in grammar talk, habet is functioning more idiomatically.

So:

• literal idea: it has the accusative
• natural grammar-English: it takes the accusative or it governs the accusative

This is a common way Latin explains grammar. A preposition has a certain case, meaning that the noun after it appears in that case.

This is one of the most important things to learn about in.

A very common rule is:

• in + accusative = motion into / onto something
• in + ablative = location in / on something

Examples:

• in urbem = into the city
• in urbe = in the city

So the difference is often:

• Where to? → accusative
• Where? → ablative

That is why the teacher says interdum accusativum habet, interdum ablativum: the same preposition can govern different cases depending on the sense.

The repetition creates a clear contrast:

• interdum accusativum habet
• interdum ablativum

This means sometimes ... sometimes ...

Repeating interdum makes the pattern very explicit and easy for learners to follow. It is a neat, balanced Latin structure.

It is a parenthetical remark meaning something like as you already know.

Here ut means as, not in order that.

That is clear because:

• scitis is indicative, not subjunctive
• the clause gives a side comment, not a purpose

So the structure is:

• main statement: In praepositio est; interdum accusativum habet, interdum ablativum
• inserted reminder: ut iam scitis

The teacher is saying this as a reminder to the class.

Because the teacher is speaking to more than one student.

Scitis is:

• 2nd person
• plural
• present
• active

So it means you all know or you (plural) know.

English usually just says you, whether singular or plural, but Latin distinguishes them:

• scis = you know (singular)
• scitis = you know (plural)

Latin often places a speech tag after the quotation, just as English can:

• ..., says the teacher

So dicit magistra is perfectly natural.

Also, Latin word order is flexible. The verb-first order can sound smooth and literary, especially in reporting speech.

So this is not strange Latin; it is simply a stylistic choice.

Because Latin has no definite article or indefinite article.

So:

• magistra can mean teacher, a teacher, or the teacher

You figure out which one is meant from the context. Here, since a specific teacher is speaking, English naturally translates it as the teacher.

Not really in the ancient sense. They are mostly modern editorial punctuation.

Classical Latin manuscripts did not use punctuation in exactly the way modern printed texts do. Textbooks and modern editions use quotation marks, commas, and other marks to make the sentence easier to read.

So the punctuation helps the learner, but it is not the main thing you are meant to study here. The important Latin grammar is in the words and forms themselves.