Answer:
I help you carry your books.
My first half means container. Not a lot of people understand my language.
I can only be played on a windy day
I am a protector. I sit on a bridge. One person can see right through me while others wonder what I hide.
I shift around though always slowly. I never move more than a few inches at a time. A large movement by me can kill many people. I am huge yet unseen by humans.
What is lighter than what it is made of?
What am I?
Animal
Difficult
Easy
Food
Funny
Kids
Logic