The lesson of the week differs for these different groups.
We began by understanding the chessboard as ranks, files, and diagonals. Each square has a name. The students learned these names. We then discussed two pieces: king and rook. Even those who had never played chess before should now know how the king and rook move. They should understand check and checkmate. We looked at checkmate from two positions. Some of the students will need additional work.
Cutting off the defending king's escape is essential to finishing the game from both positions.
White to move
White's is able to checkmate Black in two moves. First, one of the rooks moves to the seventh rank, cutting off the Black king's escape from the edge. After Black moves the king to one side of the other, the other rook moves to the eighth rank with checkmate.
White to move
Moves that put Black in check delay the end of the game. For example, 1.Rf8+ forces the defending king off the edge of the board, which is what Black wants. Cutting off the king's escape, on the other hand, ends the game quickly.
Black had only one legal move.
Advanced students were presented with a position from a game between masters, Skembris -- Gouloutis, Anogia 2015. The core of the lesson comes from a variation that might have been played. This variation is presented in the notes to the game in Chess Informant 125, which was published last week.
Black to move
The first lesson from this position is understanding that despite superficial appearances, Black's b-pawn is not protected. The a-pawn is pinned because White's queen and a1 rook both eye the rook on a8. The rook on b8 also fails to protect b4 because moving the rook would leave the a8 rook unprotected.
In the game, Black played 26...e5. The game concluded 27.Nxb4 exd4 28.Nc6 Rf8 29.Ne7+ Kh8 30.Re4 Nf6 31.Rh4+ Nh7 32.Qe4 Qc5 33.Ng6+ and Black resigned.
Although we looked at the game's actual moves, we concentrated upon the variation in the notes by Spyridon Skembris, the game's winner.
26...a4 27.Nxb4 Ra7 28.Nc6 Rxb3
White to move
How should White respond to the threat upon his queen?
The in-between move is best. This concept of an in-between move--doing something else that is forcing before taking necessary action against an opponent's threat--is often expressed by chess players with the terms zwischenzug (German) or intermezzo (Italian). This concept is the second lesson for advanced players.
We see the in-between move Ne7+ in the actual game, as well as in the variation. In the variation, however, this tactic and the multiple pins do not give White a decisive advantage as they do in the game.
The variation continues:
We also looked at the consequences of 29...Kh8, which is not discussed in the notes, to wit, 30.Re4 Rxf3 31.Rh4#.
30.Nxg6+ Kg8 31.Qe2 Qb7+ 32.d5 Nf6 and Black has counterplay that balances against White's attack.