The rule of the square is lesson 1 of 3 in Quick practice: king and pawn, an endgame course suited to players rated around 1050 (improving players). Can the king catch a running pawn? Draw a square and you know at once. It has 2 interactive exercises: 2 exercises playing out a mate. You play every move on a board and get feedback straight away. The lesson is free.
What this lesson explains
Draw a square from the pawn to its promotion square: here a4 to a8, four steps, so the square is a4-a8-e8-e4. If the defending king can step inside it, it catches the pawn. The black king on f5 is outside, and White is to move: the pawn just runs.
What you practise
Run! Promote the pawn before the king catches it.
The black king is far away on the other wing. Promote the f-pawn.
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