Who knows how that book opened?
Come on teacher! The wind blew and it open itself, and so zhun it came up on the Bernoulli principle, I am just looking at it. ( I'm lying)
Luckily she did not take it hard. Nothing happened.
So next time, make sure that your teacher is not looking when you let the wind blew your book open. ( Or just act that you're sleeping and don't care)
Just remember when someone is picking on you, don't hesitate to show the global sign language which everyone knows :

That will shut him up. If not, just dial for Children's Aid.