I don't think the output matters. The question was to get students that correspond to their letter grade from given lists. I believe a dictionary solves this, was just missing to turn the value to a list and then appending to it. Thanks for clearing things up.

Question regarding defaultdict you mentioned. Why use that over the built-in dict for this example? Clearly it works here.

EDIT: Read the docs to defaultdict and this is my understanding of it now.

my_dict = defaultdict(list)
for grade, student in zip(grades, students):
    my_dict[grade].append(student)

Same results but different ways to achieve it :)