(Portland, OR)  --  A controversial assignment at a Portland charter school was meant to be a learning opportunity, according to the school's president.  The assignment from a class at Self Enhancement Academy was broken down into three categories, "Pimp," "The B Word" and "The N Word."  President Tony Hopson told KATU, the assignment aimed to unveil why the words are inappropriate for students to use.  Hopson issued a letter yesterday apologizing to students and parents.