'Please take out A PAPER' - Surprisingly, that's a common bad command by teachers.

When it refers to the material that you write on,
'paper' is an uncountable noun.

So, it should be "Please take out a piece of paper."
or "Write your name on the back of the piece of paper."

Same goes to 'music' (a piece of music) and 'clothing' (an item of clothing)