Answer:
It's equally comfortable in an orchestra and a geometry textbook. What is it?
What is that over the head and under the hat?
There are millions of me. I am very small but when moving fast I am deadly.
Do what he says and you'll be fine, don't and you lose the game.
I can be written, I can be spoken, I can be exposed, I can be broken.
People take me on walks and I run and have fun. What am I?
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?