Stats challenge python

# 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):
    return len(dictionary)

def num_courses(dictionary):
    course_list = []
    for course in dictionary.values():
        course_list += course
    return len(course_list)

def courses(dictionary):
    course_list = []
    for x in dictionary.values():
        course_list = course_list + x
    return course_list

def most_courses(dictionary):
    max_count = 0
    teachers = " "
    for teach, m_courses in dictionary.items():
        if len(m_courses) > (max_count):
            max_count = len(m_courses)
            teachers = teach
    return teachers

def stats(dictionary):
    master_list = []
    for teacher, course_count in dictionary.items():
        return[teacher, len(dictionary.values())]