how to translate the words:"add slip"

问题描述:

how to translate the words:"add slip"
下面是上下文
i went to the class the first day it opened,and i thought that i would be added to the class beacause i was there that day.the professor said something about turning in the "add slip" right away,but i needed to get a signature for another class i was adding,so.

slip作名词的时候可以是片条,细条,板条等
例如:a slip pf paper一张纸条
add slip应该是插班条(信)吧,也就是由教这门课的系里来出,要有系的抬头纸
An add slip must be on department letterhead and come from the department that teaches the class in which you are trying to be added