Magistra discipulos monet ut ex verbis simplicibus sententiam brevem componant.

Magistra is the subject because it is in the nominative singular form. The ending -a here shows a first-declension feminine noun, meaning female teacher.

So:

• magistra = the teacher / female teacher
• it is the one doing the action of monet

That tells us the basic structure begins with: The teacher warns/advises...

Discipulos is the direct object of monet.

• discipulus = student
• discipulos = students, accusative plural

The verb moneo, monere often takes a person as its object:

• monet discipulos = she warns/advises the students

So the teacher is acting on the students.

Monet is the 3rd person singular present active indicative of moneo, monere.

It can mean:

• warns
• advises
• reminds
• sometimes urges, depending on context

In this sentence, because it is followed by ut and a subjunctive verb, advises or urges is often the most natural sense:

• Magistra discipulos monet ut... = The teacher advises/warns the students to...

After verbs like monet, Latin often uses ut + subjunctive to express what someone is urged, advised, or warned to do.

So:

• monet ut componant literally = advises/warns that they should compose
• in smoother English: advises them to compose

This is a very common Latin pattern. English often uses an infinitive (to compose), but Latin frequently prefers ut + subjunctive.

Componant is subjunctive because it is inside the ut clause after monet.

This clause expresses a command-like idea, purpose, or indirect exhortation:

• monet ut componant = she advises them to compose

So the subjunctive is not showing doubt here. It is showing that the action belongs to a dependent clause introduced by ut after a verb of advising/warning.

Because the sentence needs the present subjunctive, not the indicative.

Compare:

• componunt = they compose / they are composing
  (present indicative)
• componant = that they compose / that they should compose
  (present subjunctive)

Since ut follows monet, Latin requires the subjunctive form:

• ut ... componant

Also, componant is 3rd person plural, matching discipulos, the students.

The subject of componant is understood to be discipuli — that is, the students.

Even though the word in the main clause is discipulos (accusative, as object of monet), in sense they are the ones who will do the composing.

So the logic is:

• The teacher advises the students
• that they should compose a short sentence

Latin does not need to repeat the subject explicitly inside the ut clause, because it is clear from context and from the plural verb componant.

The preposition ex means out of or from, and it takes the ablative case.

That is why we get:

• verbis = ablative plural of verbum
• simplicibus = ablative plural of simplex, agreeing with verbis

So:

• ex verbis simplicibus = from simple words / out of simple words

This phrase tells us what the sentence is being built from.

Simplicibus is the ablative plural form, because it agrees with verbis, which is also ablative plural after ex.

Agreement in Latin means adjectives match their nouns in:

• gender
• number
• case

So:

• verbis = ablative plural neuter
• simplicibus = ablative plural neuter

Even though simplex is a third-declension adjective with a different dictionary form, it still must match verbis in the sentence.

Because it is the direct object of componant.

• sententiam = accusative singular of sententia
• brevem = accusative singular of brevis, agreeing with sententiam

So:

• sententiam brevem componant = they should compose a short sentence

The students are performing the action of composing, and the thing composed is the sentence.

Because brevem must agree with sententiam, which is accusative singular.

Compare:

• brevis = nominative singular
• brevem = accusative singular

Since sententiam is the object of componant, the adjective must also be accusative singular:

• sententiam brevem = a short sentence

Yes, but Latin word order is more flexible than English.

The sentence is:

• Magistra discipulos monet ut ex verbis simplicibus sententiam brevem componant.

A few things stand out:

• Magistra comes first, which gives prominence to the teacher.
• discipulos comes early, showing who is being advised.
• ut clearly marks the start of the subordinate clause.
• ex verbis simplicibus comes before sententiam brevem componant, which helps set up the idea from simple words before giving the result.
• componant comes at the end, which is very common in Latin subordinate clauses.

Latin uses endings, not just position, to show grammatical roles, so the meaning does not depend on word order as strictly as in English.

Not naturally in this construction.

English says:

• The teacher advises the students to compose...

Latin often does not use a bare infinitive here. Instead it prefers:

• monet ut componant

So for an English speaker, this is an important difference:

• English: advises them to compose
• Latin: advises/warns them that they should compose

This is one of those places where Latin syntax does not line up exactly with English syntax.

It breaks down like this:

Main clause

• Magistra = subject
• discipulos = direct object
• monet = main verb

Subordinate clause introduced by ut

• ut = introduces the clause
• ex verbis simplicibus = prepositional phrase, from simple words
• sententiam brevem = direct object of componant
• componant = subjunctive verb, they should compose

So the full pattern is:

• The teacher advises the students
• to compose a short sentence from simple words

That is a very useful Latin pattern to recognize: verb of advising/warning + ut + subjunctive.