Tutoring Torvald / Gerald Comes Over

S1 E14: Arnold is given the assignment to tutor Torvald, the meanest, toughest kid in Arnold's math class, for the big math test on Friday. Arnold has to find a unique way of teaching the rudiments of math to the torrid Torvald.  The two finally work together and Torvald gains a new appreciation for math and Arnold earns a reprieve from Torvald's bullying for himself and his friends. Gerald convinces Arnold to allow him to spend the night at Arnold's house. Arnold is apprehensive about introducing his friend to his extended "family"; the sometimes eccentric boarders at his Grandparents' house.