Answer:
I am one small little piece of paper yet sometimes hold lots of value. I am all you need to get in to big events but will cost you. I am an important part of travel. And if lost you're not coming.
Iron roof, glass walls, I burn and burn but never fall. What am I?
I am heavy forward, but backward I'm not. What am I?
Use me to reward good behavior.
People see through me, but none pass through without killing me. I can be anywhere, and can be seen double or single. What am I?
Give it food and it will live, give it water and it will die.
What am I?
Animal
Difficult
Easy
Food
Funny
Kids
Logic