Questions & Answers about Der erste Tag war ein echter Schock für mich.
Why is it ein echter Schock and not einen echten Schock?
Because the verb is sein (war is the past tense of sein). Verbs like sein (to be) and werden (to become) are linking verbs, meaning they connect the subject to a description in the same case (the nominative). They do not take a direct object in the accusative. Since Schock is a masculine noun in the nominative case following the indefinite article ein, the adjective gets the strong ending -er to show the gender, making it echter.
Why does the ordinal number erste just end in -e?
In German, ordinal numbers like erste (first) and zweite (second) follow the exact same declension rules as regular adjectives. Since it comes right after the definite article der, it uses weak adjective endings. For a masculine noun (Tag) in the nominative case, that weak ending is simply -e.
Why do we use mich instead of mir at the end of the sentence?
This is because of the preposition für. In German, für belongs to a specific group of prepositions that always require the accusative case. Therefore, you must use the accusative pronoun mich rather than the dative pronoun mir.
How would the word order change if I turned this into an (Even if) clause?