Holding facts

Holding Facts

I hold something

 I am strong

I have holes in me

I belong to the school

My colour is black

I am stuck to the wall

 You pick something out of me 

I am made out of steel

I start with the letter b 

When you stick me on the wall

You need screws to do it

When you pick something out of me

You put something back in me

What am I?

 by Paarth

Leave me a comment and see if you can guess what I am.