A question about a recipe: Pommes Dauphinoise (Potatoes au Gratin)

I have a question about step 3 on the recipe "Pommes Dauphinoise (Potatoes au Gratin)" from merrill. It says:

"Peel the potatoes and cut them into 1/8-inch-thick slices (I use a mandoline to get them nice and even), laying the slices on a kitchen towel to drain. Layer about a third of the potatoes in the bottom of the baking dish, fanning them into concentric, overlapping circles. Season the potatoes with salt and pepper and sprinkle a third of the cheese over them. Repeat with two more layers of potatoes, salt and pepper and cheese, making the top layer as neat and tidy as you can."

This may be a dumb question, but the potatoes are raw when you cover them with the milk and place into the oven to bake, correct?