Wir werten den Antwortbogen aus.

Because auswerten is a separable verb.

In a normal main clause, German separable verbs split into:

• the conjugated verb in position 2: werten
• the prefix at the end: aus

So:

• Wir werten den Antwortbogen aus.

But in the infinitive, it stays together:

• Wir müssen den Antwortbogen auswerten.

This is a very common German pattern:

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

Yes, there is a difference.

• auswerten usually means to evaluate, analyze, process, or assess results/data
• werten by itself is less common in everyday speech and usually means to judge, rate, or value

So auswerten is the natural verb here if you are talking about something like:

• a questionnaire
• test results
• a survey
• a form
• collected data

In this sentence, auswerten suggests more than just looking at the sheet — it means you are analyzing or evaluating it.

Because Antwortbogen is the direct object of the sentence, so it is in the accusative case.

The subject is:

• Wir = we

The thing being evaluated is:

• den Antwortbogen

Since Antwortbogen is masculine, the accusative article changes like this:

• nominative: der Antwortbogen
• accusative: den Antwortbogen

So:

• Der Antwortbogen ist lang. = The answer sheet is long.
  (der because it is the subject)

• Wir werten den Antwortbogen aus. = We evaluate the answer sheet.
  (den because it is the object)

You usually have to learn the gender with the noun, but compounds give you a helpful rule:

In German compound nouns, the last part determines the gender.

Here:

• Antwort = answer
• Bogen = sheet / form / paper

Because Bogen is masculine (der Bogen), the whole compound is also masculine:

• der Antwortbogen

This rule works very often in German:

• das Haus → das Wohnhaus
• die Tür → die Haustür
• der Plan → der Stundenplan

Antwortbogen is a compound noun made from:

• Antwort = answer / response
• Bogen = sheet / form

So it means something like:

• answer sheet
• response form
• sometimes questionnaire sheet, depending on context

German uses compound nouns very freely, so long words like this are very normal.

It is in the present tense:

• wir werten

This is the present-tense form of auswerten.

Like the English present, German present tense can have several meanings depending on context:

• We evaluate the answer sheet.
• We are evaluating the answer sheet.
• sometimes even We will evaluate the answer sheet, if the future meaning is clear from context

German often uses the present tense where English might use either the present progressive or the future.

German main clauses normally follow the verb-second rule.

That means the conjugated verb must be in the second position.

Here the order is:

1. Wir = subject
2. werten = conjugated verb
3. den Antwortbogen = object
4. aus = separable prefix at the end

So the structure is:

• Subject + conjugated verb + object + prefix

This is why you do not say:

• Wir auswerten den Antwortbogen. ✘

That form is only possible when auswerten is an infinitive, for example:

• Wir wollen den Antwortbogen auswerten.

Yes. That is correct.

German allows more flexibility in word order than English, as long as the conjugated verb stays in second position in a main clause.

So both are correct:

• Wir werten den Antwortbogen aus.
• Den Antwortbogen werten wir aus.

The second version puts more emphasis on den Antwortbogen.

What you cannot do is move things around freely and break the verb-second rule.

In normal German, you usually do need the subject pronoun.

So:

• Wir werten den Antwortbogen aus. ✔
• Werten den Antwortbogen aus. ✘

German verbs do change according to the subject, but not enough to regularly leave the subject out in ordinary sentences.

This is different from languages like Spanish or Italian, where subject pronouns are often omitted.

In a subordinate clause, the separable verb is not split. The full verb goes to the end.

For example:

• ..., weil wir den Antwortbogen auswerten.
• ..., dass wir den Antwortbogen auswerten.

So compare:

Main clause:

• Wir werten den Antwortbogen aus.

Subordinate clause:

• ..., weil wir den Antwortbogen auswerten.

This is another very important pattern with separable verbs.