Answer:
Teenage girls are pros at creating me. Learn me in classes.
If you've got me I'm everywhere. If you share me I'm nowhere. What am I?
When young I am sweet in the sun. When middle-aged I make you gay. When old I am valued more than ever.
You can see it everyday, but cannot touch it at will. What is it?
I don't have eyes, but once I did see. Once I had thoughts, but now I'm white and empty. What am I?
It rows quickly with four oars but never comes out from under his own roof. What is it?