I sat at my cousin's house for ten minutes.

The TV was on. The iPad was lit up. Toys, water guns, and broken Lego on the floor.
Her son darted from one to another, each for no more than twenty seconds.
My cousin picked up and scolded, but the kids couldn't hear.
She said: I clean up eight hundred times a day, but he just can't sit still.
I didn't say anything.
Then went to a friend's house.
Half of a puzzle on the coffee table. A dinosaur encyclopedia open on the sofa, halfway through. A few colored pens on the floor.
Her son was lying there coloring. Forty minutes. Never looked up.
She said: That's his construction site. Let it be messy.
I stood at the door, watching the two living rooms.
One looked like an exhibition hall. The other like a construction site.
The kids in the exhibition hall couldn't sit still.
The kids in the construction site couldn't be pulled away.
Later I understood—
The mess at my cousin's house is caused by the remote control.
The mess at my friend's house is built by the kids themselves.
One is arranged; the other is self-directed.
Focus isn't something you practice.
It's something that comes from not being interrupted.
It all depends on whose living room it is.