Learn Turkish: Hoca için disiplin çok önemli. - Discipline is very important for the instructor.

The word için (for) behaves differently with regular nouns than it does with pronouns. While personal pronouns need the genitive case before it (like benim için, meaning 'for me'), regular nouns like hoca just use the plain, dictionary form: hoca için.

Where is the verb 'is' in this sentence?

In Turkish, sentences describing what something is often don't need an actual verb. The phrase çok önemli (very important) acts as the whole predicate here. You could add the factual suffix -dir to the end (önemlidir) to make it sound more formal or like a universal fact, but leaving it off is the most natural choice in everyday speech.

Is there a difference between hoca and öğretmen?

Öğretmen is the standard, official word for a school teacher. Hoca is a versatile and very common word for anyone who instructs or guides you, from a university professor to a sports coach. Students in Turkey usually address their teachers directly as Hocam (My teacher).