"Το αγόρι κάθεται."

[DarrenReiley]

I don't understand how this passive. This sentence came for me in the tree under Verbs Present Passive. I see the passive ending of the verb καθεται but the meaning of the sentence does't seem passive to me. Can anyone explain?

[D_..]

Please see my answer in your other comment here https://www.duolingo.com/comment/26190139$comment_id=26190663.

[Orangus]

I read your comment there. You said:

This is how voice works in Greek grammar: an active voice verb means that the subject of the verb acts, while in passive voice the subject receives the action or is affected by it.

Although I can't see how that definition is different to English.

Given that definition, I'm still wondering how is this sentence in passive voice? Maybe it should be translated to "The boy is/was sat (down)" ?

[Tomvince]

"the boy sits down" should be accepted

[UgronHunor]

it did for me now

[Panchete1]

But... wait a minute... Does "Το αγόρι κάθεται" mean "The boy is sitting" or "The boy sits down"? Because there's a huge difference between them.