Learn Hardcore German: Am Ende des Kurses haben wir viele Fehler vermeiden können, weil die Lehrerin unsere Texte oft überarbeiten ließ. - At the end of the course we have been able to avoid many mistakes because the teacher often had our texts revised.

Genitive ending
- Kurs is masculine: der Kurs.
- The genitive singular of most masculine and neuter nouns adds -es or -s.
- For one-syllable words like Kurs, the usual form is des Kurses (with -es).
- So des Kurses = of the course.
Why genitive and not dative (like vom Kurs)
- The phrase is am Ende des Kurses = at the end of the course.
- Ende is the main noun; des Kurses depends on Ende and answers “Ende wessen?” (end of what?) → genitive.
- vom Kurs (from the course / of the course) is grammatically possible in other contexts, but here German prefers the set expression am Ende des Kurses.

So am Ende des Kurses is a very standard, idiomatic way to say at the end of the course.

Why does the sentence start with Am Ende des Kurses haben wir … instead of Wir haben am Ende des Kurses …?

Both orders are grammatically correct:

Wir haben am Ende des Kurses viele Fehler vermeiden können …
Am Ende des Kurses haben wir viele Fehler vermeiden können …

German main clauses follow the verb-second (V2) rule:

Exactly one element is put in the first position (subject, time, place, object, etc.).
The finite verb (here: haben) must be in second position.
The subject can come right after the verb.

So:

First position: Am Ende des Kurses (a time expression)
Second position: haben (finite verb)
Then: wir (subject)

Fronting the time expression Am Ende des Kurses gives it extra emphasis: At the end of the course (as opposed to earlier) we were able to avoid many mistakes.

Why is the perfect form haben wir viele Fehler vermeiden können and not haben wir viele Fehler vermeiden gekonnt?

With modal verbs (können, müssen, wollen, sollen, dürfen, mögen), German usually avoids a Partizip II form like gekonnte, gekonnt when there is another full verb involved.

Instead, German uses the double infinitive construction:

Auxiliary in present perfect: haben or sein
Main (lexical) verb: infinitive
Modal verb: infinitive at the very end

So:

Wir haben viele Fehler vermeiden können.
- haben = auxiliary (conjugated)
- vermeiden = full verb (infinitive)
- können = modal verb (infinitive, last position)

Forms like Wir haben viele Fehler vermeiden gekonnt are considered wrong or at least very unusual in standard modern German.

Why is the order viele Fehler vermeiden können and not viele Fehler können vermeiden?

In the perfect tense with a modal verb, German places the infinitives at the end of the clause in a fixed order:

Full verb infinitive(s)
Modal verb infinitive
(Sometimes other infinitives/particles in more complex structures)

So:

Fehler vermeiden können = be able to avoid mistakes
- vermeiden (to avoid) = full verb
- können (can / be able to) = modal → comes last

The pattern is:

haben (finite, 2nd position) … vermeiden können (double infinitive at the end)

Putting können in the middle (… Fehler können vermeiden) would change the structure and is not how the perfect with modals works.

Why is it viele Fehler and not sehr viele Fehler or viel Fehler?

viele Fehler
- viele is the plural form of viel used when the noun is countable and plural.
- Fehler (mistakes) is countable and here in plural.
- So viele Fehler = many mistakes.
viel Fehler
- Without plural ending, Fehler can be singular or plural in form, but viel Fehler sounds wrong here.
- For countable plural nouns you normally use viele, not viel.
sehr viele Fehler
- sehr is an intensifier: very many mistakes.
- That would also be correct, just a different nuance (stronger quantity).

So viele Fehler is the normal, neutral way to say many mistakes.

What case is viele Fehler in, and how do we know?

viele Fehler is in the accusative plural.

Reasoning:

The subject is wir (we).
The verbs are haben … vermeiden können.
We ask: haben wir was (wen/was)? → viele Fehler.
So viele Fehler is the direct object → accusative case.

Forms:

Nominative plural: viele Fehler
Accusative plural: viele Fehler (same form)

In the plural, many masculine and neuter nouns look the same in nominative and accusative, so you recognize the case from the function in the sentence, not from endings.

Why is it unsere Texte and not unseren Texte or unsren Texte?

Again, this is about case and adjective/pronoun endings:

Case and role
- In the weil-clause: weil die Lehrerin unsere Texte oft überarbeiten ließ
- Ask: ließ (wen/was) überarbeiten? → unsere Texte
- So unsere Texte is the direct object → accusative plural.
Possessive pronoun endings (plural, accusative)
- Masculine/neuter plural, accusative: unsere is the correct form.
- Declension pattern (plural):
  - Nominative: unsere Texte
  - Accusative: unsere Texte
  - Dative: unseren Texten
  - Genitive: unserer Texte

So:

unsere Texte (here: accusative plural) is correct.
unseren Texte mixes a dative/plural ending -en with the wrong noun ending and would be incorrect in this sentence.
unsren is just a colloquial shortened pronunciation/spelling of unseren you might see in informal speech, but it would still be the wrong case here.

Why is it die Lehrerin and not der Lehrer?

German distinguishes grammatical gender and natural gender:

der Lehrer = male teacher or a teacher when gender is not specified.
die Lehrerin = specifically a female teacher.

In this sentence, the teacher is specified as a woman, so German uses the feminine form die Lehrerin.

Grammar:

die Lehrerin is the subject of the weil-clause:
- weil die Lehrerin unsere Texte oft überarbeiten ließ
- Ask: Wer ließ …? → die Lehrerin → nominative singular, feminine.

Why is the verb at the end in weil die Lehrerin unsere Texte oft überarbeiten ließ?

weil introduces a subordinate clause (Nebensatz). In German subordinate clauses:

The finite verb (the conjugated verb) must be in the final position.
All other verbs (infinitives, participles) come before it.

So:

weil (subordinating conjunction)
die Lehrerin (subject)
unsere Texte (object)
oft (adverb)
überarbeiten (infinitive of the full verb)
ließ (finite verb of lassen, goes last)

Pattern:
weil + [subject] + [objects/adverbs] + [infinitive(s)] + [finite verb]

That is why you get: … weil die Lehrerin unsere Texte oft überarbeiten ließ.

What exactly does überarbeiten ließ mean, and why is it in that order?

lassen + infinitive often expresses “to have something done” or “to make/let someone do something”.

überarbeiten = to revise / to edit
lassen (preterite: ließ) = to have something done / to let

Meaning here:
die Lehrerin ließ unsere Texte überarbeiten =
the teacher had our texts revised / made (us) revise our texts.

Word order in a subordinate clause:

Infinitive of the full verb: überarbeiten
Finite form of lassen at the very end: ließ

So the correct order is:

Main clause style: Die Lehrerin ließ unsere Texte oft überarbeiten.
Subordinate clause style: … weil die Lehrerin unsere Texte oft überarbeiten ließ.

Why is ließ (simple past) used here and not hat … lassen (present perfect)?

Both tenses are possible in principle:

… weil die Lehrerin unsere Texte oft überarbeiten ließ. (preterite)
… weil die Lehrerin unsere Texte oft hat überarbeiten lassen. (present perfect; more complex word order)

Choice of tense depends on:

Region and style
- In written German, especially in narration, the Präteritum (simple past) is very common: ließ.
- hat … überarbeiten lassen is also correct, but sounds a bit heavier and is more typical in spoken language in many regions.
Simplicity
- ließ is short and clear.
- The perfect with lassen
  - another verb (hat unsere Texte überarbeiten lassen) involves multiple verbs and a tricky word order, especially in subordinate clauses.

So ließ is a natural, elegant choice in a written sentence like this.

Why is the adverb oft placed between unsere Texte and überarbeiten?

In German, adverbs of frequency (like oft, selten, immer) usually go before the main verb / verb group, but after the main objects.

In the weil-clause:

Subject: die Lehrerin
Object: unsere Texte
Adverb (frequency): oft
Verbs: überarbeiten ließ

So natural order:

… weil die Lehrerin unsere Texte oft überarbeiten ließ.

You could put oft in other positions (for emphasis), but this is the most neutral and typical placement:

After the direct object
Before the verb complex at the end of the clause

How does the overall tense and aspect compare to English in haben wir viele Fehler vermeiden können?

haben wir viele Fehler vermeiden können is present perfect in form, but the meaning is often similar to English simple past:

German: Am Ende des Kurses haben wir viele Fehler vermeiden können.
English: At the end of the course, we were able to avoid many mistakes.

Notes:

German uses the Perfekt (haben … können) very often in spoken and informal written language to talk about completed past actions, not just “past with connection to the present” as in English.
The combination vermeiden können expresses ability + completed action:
- not just we avoided mistakes, but more precisely we were able to avoid many mistakes.

So grammatically it’s perfect tense, but functionally it corresponds to English were able to avoid / managed to avoid in the past.