Castling
The one move where two pieces go at the same time: the king steps two squares towards a rook, and that rook hops over him to the far side.
Why bother
It does two useful things in one move — tucks the king into a corner where it is much harder to attack, and brings a rook towards the middle where it is actually useful. For a child, "the king hides and the rook wakes up" is enough.
The two kinds
Short castling (kingside) uses the near rook and is the common one. Long castling (queenside) uses the far rook: the king goes to c1 and the rook to d1, travelling further.
When you cannot castle
- The king has moved at any point in the game — even if it moved back.
- That particular rook has moved. The other rook may still be available.
- There is a piece standing between them.
- The king is in check right now.
- The king would pass through, or land on, a square an enemy piece attacks.
The last one catches people out: it is the king's path that must be safe. The rook is allowed to pass through an attacked square quite happily.
Teaching it
Leave castling out entirely for a child's first games. When you do introduce it, set the position up and let them make the move themselves a few times — the two-pieces-at-once part is what feels illegal to them, and doing it is more convincing than being told.
Let them practise it on a real board
- Rules are taught by playing them, not by being told them
- Blocked paths, captures and promotion each get their own lesson
- Works offline, so it is there in the car and the waiting room