Is he fishing?
No, he isn't.
What is he doing?
He's hiking a nature trail.
Is he building a fort?
No, he isn't.
What is he doing?
He's drawing.
What is she doing?
She's having a picnic.
Is she skateboarding?
Yes, she is.
What is he doing?
He's riding a bike.
What is she doing?
She's rock-climbing.
What is he doing?
He's reading a map.