Die Schule bildet Lehrer aus.

Because the verb here is ausbilden, which is a separable verb.

In a normal main clause, German usually:

• puts the conjugated part of the verb in position 2: bildet
• moves the separable prefix to the end: aus

So:

• ausbilden → Die Schule bildet Lehrer aus.

This is very common in German:

• anrufen → Ich rufe dich an.
• aufstehen → Er steht früh auf.

If you use the infinitive or a subordinate clause, the verb is usually written together again:

• Die Schule will Lehrer ausbilden.
• ..., weil die Schule Lehrer ausbildet.

No. In this sentence, aus is not a preposition.

It is the separable prefix of the verb ausbilden.

So you should understand:

• bildet ... aus = trains / educates professionally

not:

• bildet
  • aus as two unrelated words

That is an important distinction, because aus can be a preposition in other sentences, but not here.

ausbilden usually means to train, to educate, or to prepare someone for a profession or skill.

In this sentence, it means something like:

• to train teachers
• to educate teachers
• to prepare people to become teachers

It is more specific than the basic verb bilden, which can mean things like:

• to form
• to shape
• to educate in a broader or more abstract sense

So ausbilden often has a practical or professional-training sense.

Because Schule is a feminine noun in German.

Its dictionary form is:

• die Schule = school

Here, die Schule is the subject of the sentence, so it is in the nominative case.

A native English speaker may also wonder whether die means feminine singular or plural. Here it is clearly singular, because:

• Schule is singular
• the verb is bildet, which agrees with a singular subject

So:

• die Schule = the school

Because Lehrer is being used here as a bare plural: teachers.

German can do this, just like English:

• The school trains teachers.

You do not always need die before a plural noun when you mean people or things in a general sense.

Compare:

• Die Schule bildet Lehrer aus. = The school trains teachers.
• Die Schule bildet die Lehrer aus. = The school trains the teachers.
  (specific teachers)
• Die Schule bildet einen Lehrer aus. = The school trains a teacher.
  (singular)

So without an article, Lehrer is most naturally understood as plural here.

Because in this sentence, that is the natural reading.

The form Lehrer can be:

• singular: der Lehrer = the teacher
• plural: die Lehrer = the teachers

So the word form itself does not change here.

But in Die Schule bildet Lehrer aus, German normally interprets Lehrer as plural because:

• there is no singular article
• a singular accusative would usually be einen Lehrer
• the sentence sounds like a general statement about training teachers as a group

So the normal meaning is:

• The school trains teachers.

It is in the accusative case, because it is the direct object of the verb ausbilden.

The school is doing the action. The teachers are receiving the action.

So:

• Die Schule = subject, nominative
• Lehrer = direct object, accusative

A tricky point is that the bare plural form Lehrer looks the same in nominative and accusative. German learners often expect the case to show visibly on the noun, but sometimes it does not. In this sentence, you understand the role from:

• the sentence structure
• the meaning
• the verb relationship

Grammatically, Lehrer is the masculine form.

Traditionally, German often used masculine plural forms in a general way, so Lehrer could mean teachers in a mixed or unspecified sense. However, modern German is often more explicit about gender.

Possible alternatives include:

• Lehrerinnen und Lehrer = female and male teachers
• Lehrkräfte = teaching staff / teachers (more gender-neutral)

So in this sentence, Lehrer may be understood in a traditional general sense, but depending on context and style, some speakers would prefer a more inclusive wording.

Because all nouns are capitalized in German.

So:

• die Schule
• der Lehrer
• das Haus
• die Stadt

This is a standard rule of German spelling and one of the first things learners notice.

Because the subject is die Schule, which is third person singular: it / the school.

The verb ausbilden is conjugated here in the present tense:

• ich bilde aus
• du bildest aus
• er/sie/es bildet aus
• wir bilden aus
• ihr bildet aus
• sie/Sie bilden aus

So with die Schule, you need:

• Die Schule bildet ... aus.

Yes.

The German present tense often covers both:

• simple present: The school trains teachers
• present progressive: The school is training teachers

Which one sounds best in English depends on context.

So German bildet ... aus does not by itself force only one of those English translations.