TypeError: string indices must be integers, not str

[hanieh]

Hi,

I have a piece of code with the following type error:

Error:
TypeError: string indices must be integers, not str

I am new to Python and got stuck in my code. Would you please help me figure out whats the problem?
Many thanks

---

alice = {
    "name": "Alice",
    "homework": [100.0, 92.0, 98.0, 100.0],
    "quizzes": [82.0, 83.0, 91.0],
    "tests": [89.0, 97.0]
}
tyler = {
    "name": "Tyler",
    "homework": [0.0, 87.0, 75.0, 22.0],
    "quizzes": [0.0, 75.0, 78.0],
    "tests": [100.0, 100.0]
}
def get_average(student):
    homework = 0
    quizzes = 0
    tests = 0
    for key in student:
        homework =sum(key["homework"])/len(key["homework"])
        quizzes = sum(key["quizzes"])/len(key["quizzes"])
        tests = sum(key["tests"])/len(key["tests"])
    res = 0.1 * homework + 0.3 * quizzes + 0.6 * tests 
    print key["name"], float(res)
    
student = [alice,tyler]
get_average(student)