To possibly jump-start your memory, the books had a whole thing with Hermione trying to free the Hogwarts house-elves. It mostly happened in the background and

To possibly jump-start your memory, the books had a whole thing with Hermione trying to free the Hogwarts house-elves. It mostly happened in the background and they just talked about it, but it was during one of these parts we learn about the kitchen and how the food gets to the great hall.