Discipula rogat quot lineae in hoc codice scribendae sint.

The sentence has two main parts:

• Discipula rogat = The student asks
• quot lineae in hoc codice scribendae sint = an indirect question, literally how many lines are to be written in this notebook/book

So the whole sentence is:

• main clause: Discipula rogat
• subordinate clause: quot lineae ... sint

The subordinate clause is the thing being asked.

Because discipula is the subject of rogat.

• discipula = the female student / schoolgirl
• rogat = asks

Since she is the one doing the asking, discipula is in the nominative case.

Quot means how many.

It is used when asking about the number of individual countable things. Here the countable things are lineae (lines), so quot lineae means how many lines.

A useful point: quot is indeclinable, so it does not change its form for case, gender, or number.

Because lineae is the subject of sint and of the passive idea in scribendae sint.

In other words, the sentence is asking how many lines are to be written. The lines are the things that are in the state of being to be written, so lineae is nominative plural.

Also, scribendae agrees with lineae, which helps confirm this:

• lineae = feminine plural nominative
• scribendae = feminine plural nominative

Hoc codice is ablative singular after in.

Here in means in in the sense of location, so it takes the ablative:

• in hoc codice = in this book / notebook / codex

The noun is codex, codicis. Its ablative singular is codice.

So this phrase tells you where the lines are to be written.

Scribendae is the gerundive of scribo, scribere.

In this sentence it is being used in the common construction called the passive periphrastic:

• scribendae sunt = they are to be written / they must be written

Because it agrees with lineae, it is feminine plural nominative:

• linea is feminine
• lineae is plural
• therefore scribendae

So scribendae means something like needing to be written or to be written.

Because this is an indirect question, and Latin normally uses the subjunctive in indirect questions.

The direct question would be:

• Quot lineae in hoc codice scribendae sunt?
• How many lines are to be written in this notebook?

But after rogat (asks), Latin turns that into an indirect question:

• Discipula rogat quot lineae in hoc codice scribendae sint.

So sint is the subjunctive form corresponding to sunt.

Because its subject is lineae, which is plural.

• lineae ... sint = the lines ... are / may be

If the subject were singular, you would expect a singular verb.

Because this is an indirect question, not an indirect statement.

Latin usually uses:

• accusative + infinitive for reported statements
• subjunctive for indirect questions

So after rogat, if the student is asking how many lines..., Latin uses an indirect question:

• rogat quot lineae ... sint

not an accusative-and-infinitive construction.

It usually carries a sense of necessity, requirement, or what is supposed to be done.

So scribendae sint can be understood as:

• are to be written
• must be written
• need to be written

Which English translation sounds best depends on context. The Latin often has a stronger sense than a mere simple future.

Yes. The entire indirect question functions as the thing asked.

So in:

• Discipula rogat quot lineae in hoc codice scribendae sint

the whole clause quot lineae in hoc codice scribendae sint is the object or content of rogat.

Latin does not need an extra word like this or that before the clause.

The word order is quite natural for Latin, but Latin is more flexible than English.

A few things to notice:

• Discipula rogat comes first, giving the main statement.
• quot lineae comes early in the subordinate clause because it is the key question phrase: how many lines
• scribendae sint comes at the end, which is very common in Latin subordinate clauses.

So the order helps emphasize the question while still sounding idiomatic.

Yes. In Latin, codex originally means something like a book made of wooden tablets, and later more generally a book, manuscript, or similar written object.

So in hoc codice in a learning sentence is very naturally understood as something like:

• in this book
• in this notebook
• in this manuscript

It does not mean code in the modern programming sense.

The direct question would be:

• Quot lineae in hoc codice scribendae sunt?

Then if you add Discipula rogat, Latin changes it into an indirect question:

• direct: Quot lineae in hoc codice scribendae sunt?
• indirect: Discipula rogat quot lineae in hoc codice scribendae sint.

That change from sunt to sint is one of the clearest signs that the question has become indirect.