Household Logical Deductions I

(Mom from kitchen) "Where are the three pieces of cake I had kept in this plate?"

Me: We ate them.

Sis: I ate the two smaller pieces.

Me: Smaller? All were equal! Can you explain that statement of yours?

Sis: Well, you came into the room with two pieces of cake. You gave me one, which obviously had to be the smaller one. And I'm sure you would have taken the two bigger pieces of the three. So, that implies that the last piece, which I finally ate, was the smallest of all the three. Am I right?

Me: Yes, dear Holmes, you are.