Unless there is some sort of misunderstanding by me, it appears the instructions are incorrect. They ask in 01. to use an argument called "scores" it appears rather than to pass the function the grades list.
The exercise asks us to use
scores as the parameter variable so as to distinguish it from
grades. Your code works because both variables are in different scopes. However, the object (list) is one in the same for both scopes. There is only the one list.
Consequently, the code runs and passes as expected.