Learn Arabic (Modern Standard): هل أنت منسق مهرجانا؟

In this sentence, مهرجانا is the direct object of the active participle منسق. Even though منسق is a noun, it's acting with the force of a verb here ("coordinating"). Therefore, it governs its object and puts it in the accusative case, which is marked by the tanween fatha and the extra alif.

What allows the noun منسق to govern a direct object like a verb?

For an active participle (اسم الفاعل) to act like a verb and take a direct object, it usually needs to be indefinite (without ال), have tanween, and rely on a specific grammatical structure before it. Here, it relies on the preceding subject pronoun أنت. Because these conditions are met, منسق can govern مهرجانا.

Why didn't we just use an Idafa (possessive construction) here, like منسقُ مهرجانٍ?

We absolutely could! Saying هل أنت منسقُ مهرجانٍ؟ (Are you a festival coordinator?) is grammatically correct and very common. However, using the active participle with an accusative object (منسقٌ مهرجاناً) places slightly more emphasis on the ongoing action of coordinating, rather than just stating a static title or role.

How do we know منسق is an active participle and not a passive one?