Challenge task 3 of 5 : wrong in my program

def num_teachers(dictionary):
    key_count = 0
    for keys in dictionary.keys():
        key_count +=1
    return key_count
def num_courses(dictionary):
    value_count = 0
    for values in dictionary.values():
        for item in values:
            value_count+=1
    return value_count
def courses(dictionary):
    list_of_courses = []
    for value in dictionary.values():
        list_of_courses.extend(values)
    return list_of_courses

dictionary = {'Andrew Chalkley': ['jQuery Basics', 'Node.js Basics'],
                     'Kenneth Love': ['Python Basics', 'Python Collections']}
num_teachers(dictionary)
num_courses(dictionary)
courses(dictionary)