If Bumi stopped doing something based solely on the fact that someone else thought what he was doing was stupid, he'd never get anything done.

Even if she can't "see" he can't have her watching while he does this. It's too much pressure.

He keeps his focus on the piece of wood in his hand, shifts his stance until he finds what he thinks is the right position.

And then, when she gets to 10, forces everything in his reservoir of willpower to make a small ball of air to lift and spin the wood between the palms of his hands.

Rutting badgermoles, it worked!