how to translate the words:"add slip"

题目

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.

答案

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