These are the things I have learned in Chess:
- Castling Queen-side & King-side
- Forking (check and regular)
- The four-move checkmate
- En Passant
- Discovered Attacks
- The values of the pieces
A chess game is divided into 3 parts: the opening, the middlegame, and the endgame.
In the opening, it's important to castle quickly and to develop your pieces. Castling defends the king and allows the rooks to work together later on. Knights are important in the opening because they can hop over pieces on a crowded board. The most important thing is to control the middle of the board.
In the middlegame the bishops become more important.
In the endgame the rooks are very important and even a pawn if it's passed.
Queens are always important, BUT if she comes out too early your opponent can harass her all over the board while developing their pieces.