Am Wochenende mache ich mit meinem Sportverein einen kleinen Ausflug.

In German main clauses, the conjugated verb must be in second position (the “verb-second rule”), but the subject does not have to be first.

• Am Wochenende is an adverbial phrase (time).
• It is placed in the first position to emphasize when something happens.
• The verb mache still comes second.
• The subject ich is then moved after the verb.

So:

• Ich mache am Wochenende … (neutral order: subject first)
• Am Wochenende mache ich … (emphasis on the weekend)

Both are correct. The second version just highlights the time more strongly.

Am is a contraction of two separate words:

• an (preposition) + dem (dative article “the”)
• an dem Wochenende → am Wochenende

So grammatically it’s:

• Preposition an
  • dative dem Wochenende
    But in normal German it is almost always contracted to am.

For talking about days and parts of days in the sense of “on (that day)”, German normally uses an (→ am) rather than in (→ im):

• am Montag – on Monday
• am Abend – in the evening
• am Wochenende – on / at the weekend

Im Wochenende is not idiomatic in standard German when you mean “during the weekend”. Use am Wochenende for that meaning.

Wochenende is in the dative case, because of the preposition an in a time expression.

• an can take accusative or dative, but for dates and points in time, it takes dative:
  
  • am Montag (an + dem Montag) – on Monday
  • am 5. Mai (an + dem 5. Mai) – on May 5th
  • am Wochenende (an + dem Wochenende) – on the weekend

So:

• Nominative: das Wochenende
• Dative: dem Wochenende → contracted: am Wochenende

Because mit always takes the dative case, and Sportverein is masculine.

• Nominative: der Sportverein
• Dative singular: dem Sportverein

With a possessive mein-, the dative masculine ending is -em:

• mit dem Sportverein → with the sports club
• mit meinem Sportverein → with my sports club

Meinen would be:

• accusative masculine (Ich sehe meinen Sportverein – I see my club)
• or dative plural (mit meinen Freunden – with my friends),
  but here we need dative singular masculine, so meinem is correct.

Sportverein is masculine.

Clues in this sentence:

• It appears as meinem Sportverein.
• The ending -em on the possessive mein- shows dative singular masculine or neuter.
• The base noun Verein is a standard masculine noun: der Verein.

So:

• Dictionary form: der Sportverein
• Dative with mit: mit dem Sportverein / mit meinem Sportverein

Because einen kleinen Ausflug is a direct object (accusative), not the subject.

• Verb: machen
• Question: Was mache ich? – What am I doing?
  → (Ich mache) einen kleinen Ausflug.

Ausflug is:

• Masculine: der Ausflug
• Accusative singular: den Ausflug

With ein and an adjective, accusative masculine looks like this:

• ein → einen
• klein → kleinen

So:

• Nominative (subject): ein kleiner Ausflug (A small trip … does something.)
• Accusative (object): einen kleinen Ausflug (I do / make a small trip.)

Because of adjective endings in German. The pattern here is:

• Case: accusative
• Gender: masculine
• Article type: indefinite article (ein → einen)

In this situation, the adjective gets the ending -en:

• ein → einen (accusative masculine)
• klein → kleinen (agreeing with accusative masculine)

Examples:

• Ich habe einen neuen Computer.
• Er kauft einen roten Wagen.
• Wir machen einen kleinen Ausflug.

Yes, that word order is also correct.

Two common options:

1. Ich mache am Wochenende mit meinem Sportverein einen kleinen Ausflug.
   – Neutral: subject first, then adverbials, then object.

2. Am Wochenende mache ich mit meinem Sportverein einen kleinen Ausflug.
   – Emphasis on when it happens (the weekend).

Both follow:

• One element in first position (either Ich or Am Wochenende),
• Conjugated verb in second position (mache),
• The rest after that in flexible order.

You can also move the mit meinem Sportverein phrase:

• Am Wochenende mache ich einen kleinen Ausflug mit meinem Sportverein.
  Still correct; the nuance of emphasis changes slightly, but the meaning is the same.

German often uses the present tense to talk about the near future, especially for planned or scheduled actions.

So:

• Am Wochenende mache ich …
  literally: “On the weekend I do …”
  but naturally understood as: “I’m going to do … this weekend.”

You could say:

• Am Wochenende werde ich mit meinem Sportverein einen kleinen Ausflug machen.

That’s grammatically fine, but in everyday speech the simple present (mache) is more common for this type of plan.

In German, all nouns are capitalized, regardless of where they appear in the sentence.

• Ausflug is a noun, so it must start with a capital letter.
• The same is true for Wochenende, Sportverein, etc.

This is a standard spelling rule: every noun → capital letter.