Answer:
I regularly change shape yet remain a sphere. I am always there but not often seen. What am I?
I will disappear every time you say my name.
I am the best thing that can happen after a stick hits a ball.
What goes up and down stairs without moving?
I help you carry your books.
No matter how little or how much you use me, you change me every month.
What am I?
Animal
Difficult
Easy
Food
Funny
Kids
Logic