Chess notation cheat-sheet (for new readers)
Pieces: K king · Q queen · R rook · B bishop · N knight · (a pawn move has no letter)
Actions: x takes · + check · # mate · O-O short castles · O-O-O long castles · e8=Q pawn promotes to queen
Annotations: ! good move · !! brilliant · ? mistake · ?? blunder
Treat the two-square push as an alarm
In these positions the capture window is one move wide, so the discipline you train is noticing it before you reach for a quieter plan. The moment an enemy pawn jumps two squares and lands beside yours, the option is live for this turn only, and it vanishes if you spend a move improving your pieces first. (For the exact legality conditions, the lead links the rule page.) Your job at the board is to react to that fresh push instead of scrolling past it.
So build one habit: when a pawn arrives next to yours after a double step, stop and ask whether grabbing it in passing leads anywhere. Most solvers fail these not because the move is hard to play but because they never check for it. Run the question on every position in this set and the alarm becomes automatic, which is the whole point of drilling the motif in bulk rather than meeting it once a year in a real game.
Reconstruct the last move from the still position
The board never flags which pawn just moved, so the solving skill here is rebuilding the last move from a frozen picture. Two cues do most of the work. The enemy pawn sits level with yours rather than one square ahead, the giveaway that it sprinted past the square where you could have stopped it. And nothing stands on the square it would have crossed, since it leapt over that square instead of stepping through it. Read both and you know the capture in passing is on the table.
Practice reading those cues fast, because the puzzle clock rewards it. The positions come from computer-verified games, so every capture you spot actually came up over the board rather than in an invented diagram. That matters for training: you are rehearsing the exact recognition pattern a real opponent will hand you, not a textbook setup that never occurs.
Solve from the empty lane backward
The capture is rarely about the pawn. It is about the line that opens once the pawn is gone, so solve these from the back forward. Picture the board after the pawn vanishes, find what your rooks, bishops, or queen suddenly hit down the cleared file or diagonal, then play the capture that opens it. Sometimes the capture is itself a discovered check, because sliding your pawn off its square unveils a piece behind it. Spotting the finish first and the capture second is faster than the reverse.
That back-to-front method is what this set drills and a plain rule page cannot. A few positions end in mate the instant the file clears, the same idea behind the Gundersen versus Faul finish of 1928, where a capture in passing opened the path to checkmate. Others win a stranded piece or halt a passed pawn near promotion. Slide the rating from 400 to 2400 and the set meets you near a 75 percent solve rate, with three free hints, the motif first, then the piece, then the move, when a position will not crack.