Can a queen beat a pawn that is one step from promoting?
Usually yes. A queen and king beat a king and pawn, even when the pawn is one square from the last rank.
Each player counts ranks from their own side of the board. A black pawn on d2 is on Black's seventh rank, so it needs one move to promote.
The queen alone cannot stop the pawn forever. The white king has to walk over and help. The whole method is about finding the time for that walk.
How does the queen win?
The method is a loop of three steps. Repeat it until your king has arrived.
1. Check the enemy king from a square where the queen also watches the promotion square.
2. Force the king in front of its own pawn. Standing there, the king blocks the pawn, so the pawn cannot move.
3. Take a free move with your king. The pawn is blocked, so nothing bad happens while you walk one square closer.
In the study White plays 1.Qc4+ Kd1 and then 2.Kf6. That king move is the point of the whole check. Every trip round the loop earns one more step.
Why does a bishop's pawn only draw?
A pawn on the c-file or the f-file is called a bishop's pawn, because a bishop starts on that file.
Against those pawns the defender has a trick. Instead of stepping in front of the pawn, the king runs into the corner.
In the study Black answers 1.Qb4+ with 1...Ka2, and later goes to a1. White would like to take the pawn on c2, and cannot. With the black king on a1, that capture leaves Black with no legal move and no check, which is stalemate and a draw.
So White never gets the free move, and the black pawn promotes.
Why does a rook's pawn only draw?
A pawn on the a-file or the h-file is called a rook's pawn. Here the defence is even simpler.
The black king goes to a1, the square its own pawn wants, so the pawn cannot move. Look at what the white queen can do.
- Taking on a2 loses the queen, because the king simply takes it back.
- Any move that keeps the queen guarding b1 and b2 leaves Black with no legal move, which is stalemate.
So White has to step back and let the black king out, and the position never changes.
When do the draws stop being draws?
Both draws depend on the attacking king being far away. In our positions the white king starts on g7, which is too far to help.
If the white king is already near the corner, the stalemate trick fails. The king covers the squares that would otherwise be stalemate, and the queen wins.
So there is no easy rule for the defender either. Look at where the enemy king stands before you decide the position is safe.
The mistake we see learners make
Learners check the enemy king from anywhere, hoping something turns up.
A check only helps when it forces the king onto the square in front of its own pawn. If your check pushes the king sideways, you have spent a move and gained nothing.
The second mistake is capturing a pawn without counting the enemy king's squares. Look before every capture. If the enemy king is in a corner with nothing to move, your capture has drawn the game.