Learn Hardcore Russian: Концерт оказался интересным. - The concert turned out to be interesting.

Оказался is the past tense (masculine singular) form of the pronominal verb оказаться. It translates roughly to "turned out" or "proved to be", indicating that the quality of being interesting was revealed over time or unexpectedly.

Why is the adjective интересным in the instrumental case?

In Russian, when a predicate adjective follows a linking verb like оказаться, it is typically put in the instrumental case. The instrumental интересным shows the resulting state of the subject—here, that the concert ended up being interesting—much like saying "turned out to be interesting" in English.

What is the purpose of the -ся ending in оказался?

The -ся ending marks the verb as pronominal. In the case of оказаться, it isn’t used to indicate a reflexive action in the usual sense; instead, it is an essential part of a fixed expression that conveys the idea of something turning out or proving itself to be a certain way.

Could I replace оказался with был? What difference would that make?

Yes, you can say Концерт был интересным to mean "The concert was interesting." However, using оказался adds nuance by emphasizing that the interesting quality became apparent over time or unexpectedly, rather than merely stating a fact.

Is it acceptable to change the word order, for example, saying Интересным оказался концерт?

Absolutely. Russian word order is flexible. Интересным оказался концерт is grammatically correct and can be used to place emphasis on the adjective интересным, highlighting the surprising or notable nature of the concert's quality.