Magister discipulos verba nova in charta scribere iubet.

Because iubet means orders or commands, and after iubet Latin commonly uses an infinitive to express the action being ordered.

So:

• iubet = he orders
• scribere = to write

Latin says, literally, something like:

• The teacher orders the students to write...

A learner might expect a clause like that the students write, but Latin often prefers person + infinitive after iubeo.

Discipulos is accusative because it is the person being ordered.

With iubeo, Latin typically puts:

• the person ordered in the accusative
• the action ordered in the infinitive

So:

• magister = the teacher
• discipulos = the students
• scribere = to write

This is a very common pattern:

• Magister discipulos scribere iubet = The teacher orders the students to write

In sense, it is both.

• Grammatically, discipulos is the accusative dependent on iubet
• Logically, discipulos are the ones doing the writing

So in English we think:

• The teacher orders the students [to write]

The students are the people ordered, and they are also the understood subject of scribere.

This is a normal Latin construction.

Because verba nova is the direct object of scribere.

The sentence tells us what the students are being ordered to write:

• verba nova = new words

Since scribere takes a direct object, that object goes in the accusative.

So the structure is:

• discipulos = the students, who are to do the writing
• verba nova = the things to be written

Because nova must agree with verba.

Verbum is a neuter noun. Its accusative plural is verba. Therefore the adjective modifying it must also be:

• neuter
• plural
• accusative

That gives us nova.

So:

• verbum novum = a new word
• verba nova = new words

This is adjective agreement: the adjective matches the noun in gender, number, and case.

Because verba is the neuter plural of verbum.

Latin neuter nouns of the second declension often have:

• singular nominative/accusative in -um
• plural nominative/accusative in -a

So:

• verbum = word
• verba = words

This is a very important pattern in Latin.

Other examples:

• bellum = war, bella = wars
• donum = gift, dona = gifts

Because in with the ablative usually indicates location:

• in charta = on the paper or in/on the sheet

Here the idea is not motion into something, but location or place where the writing appears.

A useful rule is:

• in + ablative = in/on a place
• in + accusative = into/onto a place

So:

• in charta = on the paper
• if it were motion onto the paper, Latin could use a different construction

Because the Latin infinitive itself already means to write.

In dictionary form:

• scribere = to write

So Latin does not need a separate word corresponding to English to here. The ending -re already marks the infinitive.

Other examples:

• amare = to love
• videre = to see
• audire = to hear

Latin word order is much freer than English word order because the endings show each word’s grammatical role.

Putting iubet at the end is very natural in Latin. In fact, Latin often likes to place the main verb late in the sentence.

This order also builds the thought nicely:

• Magister — subject
• discipulos — the people being ordered
• verba nova — what they must write
• in charta scribere — the action
• iubet — finally, the main verb: orders

So the word order is not random, but it is more flexible than English.

Yes, often they could.

Because Latin uses case endings, many rearrangements would still be understandable. For example, forms like these would still express basically the same idea:

• Magister iubet discipulos verba nova in charta scribere
• Discipulos magister verba nova in charta scribere iubet
• Verba nova magister discipulos in charta scribere iubet

However, changing the order can change emphasis or style.

The original sentence is a very natural, straightforward Latin order.

Because classical Latin has no articles.

Latin usually does not have separate words for:

• the
• a/an

So:

• magister can mean the teacher or a teacher
• discipulos can mean the students or students
• charta can mean the paper, a paper, or simply paper, depending on context

English must choose an article, but Latin often leaves that to context.

They are:

• magister, magistri — teacher
• discipulus, discipuli — student, pupil
• verbum, verbi — word
• novus, nova, novum — new
• charta, chartae — paper, sheet, page
• scribo, scribere, scripsi, scriptum — write
• iubeo, iubere, iussi, iussum — order, command

Knowing the dictionary forms helps you see why the sentence has these exact endings:

• magister = nominative singular
• discipulos = accusative plural
• verba = accusative plural neuter
• nova = accusative plural neuter agreeing with verba
• charta = ablative singular after in
• scribere = present active infinitive
• iubet = 3rd person singular present active

Yes, in a broad sense it is a very similar kind of pattern.

After iubeo, Latin commonly uses:

• an accusative for the person involved
• an infinitive for the action

So in:

• Magister discipulos ... scribere iubet

the accusative is discipulos, and the infinitive is scribere.

A learner may later meet the more famous accusative-and-infinitive construction in indirect statement, but this sentence already shows the same important idea: Latin often uses an accusative noun + infinitive where English might use a full subordinate clause.