How to append input value into list?

import math

#Function that gets the average
def Average(homework):
    return float(sum(homework)) / len(homework)

# grades
homework = [100, 95, 100, 90]
classwork = [80, 100, 75, 80]
assessments = [95, 67, 82]

# added this below
gradebook = {'homework': homework, 'classwork': classwork, 'assessments': assessments}
categories = list(gradebook.keys())

# added loop to allow multiple grade additions
print("------------Additional Grades-----------------")
while True:
    additional = input("Would you like to insert a grade?  ")
    if additional == 'yes':
        # notice we can easily use "categories"
        category = input("Please choose a category {}:  ".format(categories))
        if category in categories:
            # print grades in category
            print("current grades in {}: {}".format(category, gradebook[category]))
            score =  input("{} grade you wish to input (must be a number) :  ".format(category))
            # convert the score from string to a number
            try:
              score = float(score)
              # notice we add the score to the gradebook category.
              gradebook[category].append(score)
            except:
              print("Error: score must be a valid number.")
        else:
            print("That is not a valid category")
    else:
        # this causes us to exit the loop
        break


average1 = Average(homework)
print("Average of homework =", round(average1, 2))

average2 = Average(classwork)
print("Average of classwork =", round(average2, 2))

average3 = Average(assessments)
print("Average of assesments =", round(average3, 2))

#Adding weights to each category (10%, 30%, 60%)
weightedAverage = average1 * 0.1 + average2 * 0.3 + average3 * 0.6
print("-----------------------------")
print("Your overall grade is : ", round(weightedAverage, 2))