Strange detachment

I sit at a school desk and look around
There are laughing voices and insignificant prattle
A detached feeling comes over me
Someday no one will remember this very day had happened
Why am I sitting here watching?
I will only forget in a matter of days.
After all, I find meaning in my existence from only what I can remember
Why does something matter if no one remembers?
Why does it happen in the first place?