teachers.py challenge task 3 of 5. Passes the console, but not the challenge. Any ideas?

# 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.
teachers = {"Kenneth Love" : ["Python Basics", "Python Collections"], "Andrew Chalkey": ["JQuery Basics", "Node.js Basics"]}

def num_teachers(teachers):
    return len(teachers)

def num_courses(teachers):
    total = 0
    for i in teachers:
        total += len(teachers[i])
    return total

def courses(teachers):
    courses1 = teachers.get("Kenneth Love")
    courses2 = teachers.get("Andrew Chalkey")
    courses1.extend(courses2)
    return courses1