The method
Black's pawn is one step from queening, and the white king on h8 is far away. The queen cannot stop the pawn by force at once, but it can gain time with checks and pins.
Keep checking until the black king has to stand on e1, in front of its own pawn. Then the pawn cannot move, and White has one free move. Spend it on bringing the king one step closer, then start the checks again.
Repeat the cycle until the white king is close enough to help win the pawn or mate.
Which pawns lose
The method works against a centre pawn (on the d- or e-file) and a knight's pawn (on the b- or g-file). The defender has no way out: the only way to keep the pawn is to block it with the king.
Against a bishop's or rook's pawn the defender has a stalemate defence, and with the attacking king far away the result is a draw. That is the next lesson.
Typical mistakes
In the starting position only checks win: Qb1+, Qb3+, Qd6+ and Qd8+. Every quiet queen or king move gives up the win.
Do not take the pawn while the king defends it. And when the king finally stands on e1, Qxe2+ throws the queen away: the free move belongs to your king.
Remember
- Check or pin to gain time
- Force the king in front of the pawn
- Use the free move for your king
- Repeat until the king arrives