The way to say this is pololi au, but apparently, the lesson is to teach the idiomatic statement over the more straightforward one.
On the one hand, there is the learning of the grammar. But equally important is the learning of Hawaiian thinking.
Why no "au"?
It is an idiomatic expression like (My stomach is growling.) which means: I am hungry.
The sentenceʻs literal means is: The stomach is hungry.
How would you turn that around into a question?
kinda similar in Japanese "お腹がすきました"