i don't understand what i am doing wrong here

The problem is with the last two lines. You should change them to:

sorted_things = favorite_things[:]
sorted_things.sort()

Notice the [:] in front of the favorite_things. This is used to make a copy of favorite_things. If we didn't use that, later when we sort the sorted_things list, it will sort both the sorted_things AND favorite_things! The reason is a little bit complicated, but think of it as this. When we assign sorted_things to favorite_things itself, this is what Python will think:

favorite_things ----------->   ['raindrops on roses', 'whiskers on kittens', 'bright copper kettles', ...]
                                               ^
                    |--------------------------|
sorted_things ------|

As shown, Both the favorite_things and sorted_things are pointing to the same list. So if we change either variable, both of them will be changed. When we make a copy, Python will think this way:

favorite_things -------> ['raindrops on roses', 'whiskers on kittens', 'bright copper kettles', ...]


sorted_things -------> ['raindrops on roses', 'whiskers on kittens', 'bright copper kettles', ...]

I hope this helps. ~Alex