One of the things that I like about chess is that even very basic positions with few pieces on the board can be interesting.   I’ve been teaching one of my classes about “the square” in King and pawn endings where the King can stop the pawn from queening if it can enter the imaginary square (e.g. if White has a pawn on a5 imagine a square from a5 – a8 – d8 – d5 – a5).   The puzzle that I gave them today was the diagram below with White to play.   Is Black’s King in the square and can he stop White’s “a” pawn?   That is today’s puzzle.

8/5p2/4p3/8/3P4/5k2/P7/5K2 w – - 0 1White to Play - what result?

ANSWER:

After 1.a4 Kd5 2.a5 Kd5 3. a6 Kc6 Black’s King will capture the passed pawn as Black’s King is in “the square”.

If White understands this at the start he may find 1.d5! exd 2.a4 and now even though Black’s King is still in the square he is blocked by his own pawn and can’t stop White from queening.   Play should continue 2…d4 3.a5 d3 4.Ke1 and White wins.