Frans van Schooten developed the Cartesian Plane in 1649 as a tool for explaining Rene Descarte's brilliant La Géométrie.
Centuries later, I think it could stand some improving. First, fix the labelling of the quandrants.
Get rid of the Roman numerals. Instead, use Hindu-Arabic numerals. Start the numbering with
The two most significant bits of an angle in cycles give the quadrant.
Second, make the angles proceed in a clockwork fashion. My reservation about this change in direction is that analog clock faces are obsolete. I don't know if future children will think of clockwise rotation as a preferred kind of rotation.