Right, the 2-sphere is the surface of the 3-ball. I think "volume of a sphere" is okay though. It just means the volume enclosed. >a cube in 3 dimensional spac

Right, the 2-sphere is the surface of the 3-ball. I think "volume of a sphere" is okay though. It just means the volume enclosed. >a cube in 3 dimensional space is always considered to be 3 dimensional. So "cubes" are taken to include their interior. That makes sense I suppose. I wonder what the surface of a cube is called. A "box" maybe?