Answer:
What is given but kept by the giver?
I am the greatest teacher out of them all, but alas in the end I kill my pupils.
It is a sound of empty, speak and it'll talk back plenty. But all the more you yack, you'll get the same words back.
Hold the tail, while I fish for you.
Used left or right, I get to travel over cobblestone or gravel. Used up, I vie for sweet success, used down, I cause men great duress.
It weighs next to nothing but no one can hold it for long. What is it?
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?