Chalk Drawings Left Behind

Hidden messages
Burried deep inside many layers of writing.
A black layer of nothing
Once used to fill the rectangle
Just a mere blank board
Til many years of students
Cover the board with useless
Messages
And pictures.
Colors flow through the once blank baord
And make a collage of the students.
Who would think a blackboard
Could be filled with meaningful chalk messages.
But then the board is erased
The chalk drawings become hidden
Deep inside the board
And they are replaced by the smudges
Meaningless
Unlike the chalk drawings that had
Once lay there before.