The Skewer
How to spot it: look for the enemy king or queen on an open line with something worth taking directly behind it. Give a check or a threat along that line: when the front piece steps aside, collect the one behind.
How to recognise it in a game
Look for a king or queen standing in front of a rook, bishop or loose piece on the same rank, file or diagonal. A forcing attack on the front piece makes the target behind it vulnerable.
The common calculation mistake
Players often notice the alignment but forget that the front piece may capture the attacker, block the line or move while protecting the rear target. Calculate the forced reply before assuming the second piece falls.
How to defend against it
Avoid placing two valuable pieces on one exposed line. If skewered, search for a square that moves the front piece with tempo, protects the rear piece, or interrupts the attacking line.
Now spot it yourself
A real position: find the move. This is exactly what the drills in the app do, banded from beginner to expert.
How this lesson is made: this public explanation comes from the authored Strong Squares curriculum. Automated checks protect its chess data, source fields and learning flow. Independent chess-editor approval remains part of the private-preview release process. Read the teaching method.