What am I doing wrong here? Creating a new list from a list: [teachers, # of classes]

# The dictionary will look something like:
# {'Andrew Chalkley': ['jQuery Basics', 'Node.js Basics'],
#  'Kenneth Love': ['Python Basics', 'Python Collections']}
#
# Each key will be a Teacher and the value will be a list of courses.
#
# Your code goes below here.
def num_teachers(dictionary):
    count = len(dictionary.values())
    return count
def num_courses(teachers_courses):
    list_courses = []
    for courses in teachers_courses.values():
        list_courses.extend(courses)
    return len(list_courses)
def courses(dictionary):
    single_list = []
    for courses in dictionary.values():
        single_list.extend(courses)
    return single_list
def most_courses(dictionary):
    max_value = 1
    for key in dictionary:
        if len(dictionary[key]) > max_value:
            max_value = len(dictionary[key])
            max_key = key
    return max_key
def stats(dictionary):
    master_list = []
    for keys, values in dictionary.items():
        master_list.append([key, len(value)])
    return master_list