Worksheet: Rule of the Square

Use an imaginary square to decide quickly whether a king can catch a running pawn.

Why This Matters

• Count how many moves the pawn needs to promote. That number helps make the sides of the square.
• If the defending king can step inside the square, it can usually catch the pawn.
• The rule is a shortcut, but you should still check the actual moves when kings are close.

Practice Tasks

1. Explain what the square starts from and how wide it is.
2. Why is the rule of the square useful even before you calculate every move?
3. Play out the three races and write whether the king catches the pawn or the pawn escapes.

Board Evolution (One Step per Board)

Practice Positions

Find each move on paper, then check the Answer Key at the end.

Mini-Game

Play this with a partner. Before each king move, point to the imaginary square of the pawn and say whether the king is inside it or outside it.

Answer Key

1. The square starts on the pawn’s square and reaches to the promotion rank with the same width as height.
2. It gives a fast yes-or-no answer before you calculate every move in detail.
3. Practice 1: king catches. Practice 2: pawn escapes. Practice 3: king catches.

Practice Position Solutions

1. Practice 1: Kd4 c3 Kxc3 — The king steps into the square in time and catches the pawn on c3.
2. Practice 2: Kf2 c1=Q — White is too far away. The pawn reaches the last rank before the king can catch it.
3. Practice 3: Kc3 a4 Kb4 a3 Kxa3 — Even against the rook pawn, White stays close enough to enter the square and capture it on a3.