← The Arithmetic of the Chessboard · Lesson 1 of 3
Coordinates
Every square has a name: a letter for the file (a to h, left to right from White’s side) and a number for the rank (1 to 8, from White’s side up). The white king starts on e1.
That is the same idea as a map grid or a graph: two numbers, one across and one up, pick out exactly one place.
A knight moves two squares in one direction and one at right angles. From d4, which of these can it reach?
A lesson is kept once you've answered the question and written at least 8 words. Nobody grades it; it stays on this device.