1.

[So you've already seen an example of the skewer in the last problem of the fork section. Pins and skewers are both versions of an x-ray attack, where the attacker has two defenders piled up in its line of fire. A skewer is more forcing, because the more valuable piece is attacked first and when it moves, the less valuable piece can be captured. For example, take a look at this position. 

Here white can play rook H8 check, and when the black king moves to G7, F7, or E7, rook takes A8 wins the queen. This is a decisive skewer. 

A pin, in contrast, is when the less valuable piece is attacked first, but is pinned to its square because, if it moves, the more valuable piece would fall. For example, here.

The black knight is pinned and can't move, because then the king would come under attack. So black is paralyzed and will lose the knight. 

It's important to realize the only bishops, rooks, and queens can pin or skewer, because they are the only long distance operators. Let's start off working on some skewers.

{B:q2k4/8/8/1N6/8/8/1P6/3KR3}{D:1000}{S:e1e8}{A:Ce8d8}{A:Dd8a8}{D:9000}{R}{S:d8d7}{D:500}{S:e8a8}{D:2000}{S:a8e8}{P:BQa8}{D:500}{S:d7d8}{A:Ce8d8}{A:Dd8a8}{D:5000}{B:q4k2/8/8/8/8/8/8/3K3R}{W:261a}{B:q4k2/8/8/8/8/8/8/3K3R}{D:1000}{S:h1h8}{A:Ch8f8}{A:Df8a8}{D:2000}{R}{S:f8f7}{A:Ch8a8}{D:2000}{R}{S:h8a8}{W:261b}{B:4k3/8/8/8/4n3/8/8/K3R3}{D:2000}{A:Ce1e4}{D:3000}{H:e8}{W:261c}{B:4k3/8/8/8/4n3/8/8/K3R3}{D:1000}{A:Ce1e4}{A:De4e8}{D:7000}{G:WBh1}{G:BRc6}{D:500}{A:Ch1e4}{A:De4c6}{D:1000}{G:WQb1}{G:BRg6}{A:Cb1e4}{A:De4g6}{W:261d}{W:261e}

]

2.

[

{B:Q7/8/8/2k5/4K3/8/1r6/5b2 b}{V:{SAVE}It's black to move here. Find the skewer. {W:262a};

$Bishop C2 check skewers the king to the queen.

  {S:f1g2}{A:Cg2e4}{A:De4a8}{W:262c}

  {R}{S:e4e5}{S:g2a8}{W:sil1000}{W:sil1000}{J}

$f1g2;That's right! Bishop C2 check skewers the king to the queen...

  {A:Cg2e4}{A:De4a8}{W:thatsright}

  {W:262c}{R}{S:e4e5}{S:g2a8}{W:sil1000}{W:sil1000}{J};

$c Incorrect.{W:notquiteit2}{RETRY};

Remember, in a skewer the more valuable piece is attacked first, and when it moves the less valuable piece can be captured.}

]

3.

[

{B:4r1k1/5p1p/6p1/3p4/4q3/R6P/5PP1/3Q2K1 w}

{V:{SAVE}Now it's white to move. Find the skewer.{W:263a};

$Here white can play rook E3. The rook is defended by the F2 pawn. So after queen E3, F takes E3, white has one a queen for a rook. There's no way for the black queen to move to a square that defends her rook, because the A4 square is guarded by the white queen.

  {S:a3e3}{A:Ce3e4}{A:De4e8}{D:3000}{A:Gf2e3}{D:3000}{R}{S:e4e3}

  {D:1000}{S:f2e3}{D:3000}{S:e3f2}{P:BQe3}{S:e3e4}{P:WRe3}{H:a4}{G:BQa4}

  {A:Ne4a4}{A:Cd1a4}{A:Na4e8}{W:263b}{W:263c}{W:sil1000}{J}

$a3e3;Very good! Here white can play rook E3. The rook is defended by the F2 pawn. So after queen E3, F takes E3, white has one a queen for a rook. There's no way for the black queen to move to a square that defends her rook, because the A4 square is guarded by the white queen.

  {A:Ce3e4}{A:De4e8}{D:3000}{A:Gf2e3}{D:3000}{R}{S:e4e3}{D:1000}{S:f2e3}

  {D:4000}{S:e3f2}{P:BQe3}{S:e3e4}{P:WRe3}{H:a4}{G:BQa4}

  {A:Ne4a4}{A:Cd1a4}{A:Na4e8}{W:verygood}{W:263b}{W:263c}{W:sil1000}{J};

$cIncorrect. Remember, for a skewer the more valuable piece is attacked first, and when it moves the less valuable piece can be captured.

  {W:notquiteit2}{RETRY};

d1c2:$cIncorrect. While this is a skewer, your queen can be captured by the black queen - Qxc2.{D:1000}{S:e4c2}{W:notquiteit2}{RETRY};

d1b1:$cIncorrect. While this is a skewer, your queen can be captured by the black queen - Qxb1.{D:1000}{S:e4b1}{W:notquiteit2}{RETRY};

d1e1:$cIncorrect. While this is a skewer, your queen can be captured by the black queen - Qxe1.{D:1000}{S:e4e1}{W:notquiteit2}{RETRY};

Look for a rook move.}

]

4.

[

{B:8/2q5/r3k3/2p2p1p/1pP1p1p1/1P5P/3Q1PP1/1R4K1}{V:{SAVE}White to move here. Do you see the skewer?{W:264a};

$Queen H6 check. Here you can really see the power of combining the queen's diagonal and horizontal powers. She can slice through the enemy pawn structure to move to the H file to win the black rook all the way on the a-file.

  {S:d2h6}{G:WQd2}{A:Nd2h6}{A:Ch6e6}{A:De6a6}{D:7000}{R}{O}{S:e6e5}

  {D:1000}{S:h6a6}{W:264b}{W:sil1000}{J}

$d2h6;Very good! Queen H6 check. Here you can really see the power of combining the queen's diagonal and horizontal powers. She can slice through the enemy pawn structure to move to the H file to win the black rook all the way on the a-file.

  {G:WQd2}{A:Nd2h6}{A:Ch6e6}{A:De6a6}{D:7000}{R}{O}{S:e6e5}

  {D:1000}{S:h6a6}{W:verygood}{W:264b}{W:sil1000}{J};

$c Incorrect. Remember, for a skewer the more valuable piece is attacked first, and when it moves the less valuable piece can be captured.{W:notquiteright}{RETRY};

Think about the value of the pieces. Which piece of high value can you attack?}

]

5.

[

{B:r7/8/2k1q3/3p1Q2/2pP1K1p/2P4P/8/5R2 b}

{V:{SAVE}Here black has to decide whether or not to trade queens. Do you see how to set up a skewer? Usually in chess games, our opponents don't just serve us up positions where we could use tactics to beat them. We have to prepare them. Take a look. Black to move.{W:265a};

$It turns out that by trading queens, black can win a rook. After queen takes F5 check, king takes F5, rook F8 check wins a rook. Now that you know about skewers, your alarm bells should always go off when you notice pieces lined up on the same diagonal, rank, or file. This is how the chess intuition works. We learn patterns and then instinctively put them together.

  {S:e6f5}{D:5500}{S:f4f5}{D:1000}{S:a8f8}{A:Cf8f5}{A:Df5f1}

  {D:1500}{R}{S:f5g5}{S:f8f1}{W:265b2}{W:sil1000}{J}

$e6f5;That's right! It turns out that by trading queens, black can win a rook. After queen takes F5 check, king takes F5, rook F8 check wins a rook. Now that you know about skewers, your alarm bells should always go off when you notice pieces lined up on the same diagonal, rank, or file. This is how the chess intuition works. We learn patterns and then instinctively put them together.

  {D:6000}{S:f4f5}{D:1000}{S:a8f8}{A:Cf8f5}{A:Df5f1}

  {D:1500}{R}{S:f5g5}{S:f8f1}{W:thatsright}{W:265b2}{W:sil1000}{J};

$cIncorrect. Remember, for a skewer the more valuable piece is attacked first, and when it moves the less valuable piece can be captured.{W:notquiteright}{RETRY};

The intro to this exercise mentioned something about trading queens…}

]

6.

[

{B:8/3q1N2/3p4/8/8/3k4/6K1/Q7 w}{V:{SAVE}This last one is a little tricky. It's okay if you can't get it, but I want you to try for a few minutes. Try to combine some of the ideas we've been talking about. White to move here. Any ideas?{W:266a};

$Knight E5 check. A great move! You see, white sacrifices with a fork to set up a skewer. The black pawn on D6 defends the E5 square. After D takes E5, now what should white play? Queen D1 check wins a queen. You see, if we learn these patterns - forks, skewers, and others - in time, our intuition will tell us how to combine them.

  {S:f7e5}{D:1000}{A:Ce5d7}{A:Ce5d3}{D:5000}{A:Cd6e5}{H:e5}{D:2000}{R}{C}

  {D:1000}{S:d6e5}{D:3000}{S:a1d1}{A:Cd1d3}{A:Dd3d7}{D:3000}{R}{S:d3e4}

  {D:1000}{S:d1d7}{W:266b}{W:266c}

$f7e5;Well done! Knight E5 check. A great move! You see, white sacrifices with a fork to set up a skewer. The black pawn on D6 defends the E5 square. After D takes E5, now what should white play? Queen D1 check wins a queen. You see, if we learn these patterns - forks, skewers, and others - in time, our intuition will tell us how to combine them. 

  {D:1000}{A:Ce5d7}{A:Ce5d3}{D:5000}{A:Cd6e5}{H:e5}{D:2000}{R}{C}

  {D:1000}{S:d6e5}{D:3000}{S:a1d1}{A:Cd1d3}{A:Dd3d7}{D:3000}{R}{S:d3e4}

  {D:1000}{S:d1d7}{W:welldone}{W:266b}{W:266c};

$c Incorrect. This one is tricky, and involves several concepts. Think carefully and plan ahead.{W:notquiteit2}{RETRY};

You have to combine forks and skewers to sacrifice and then win the black queen.}

]

