I noticed several readers are keen on the topic of Board Orientation, or Examination by some authors. To examine the roles of each piece in play is indeed something that's so important in determining one's decision that it is not much mentioned in chessbooks. So far, only Dan Heisman's Everyone's Second Chess Book has delved into this topic.
The other source of board vision drills that I would advocate is Michael De La Maza's Concentric Square exercise. Start by placing a Black King on a centre square say d5 Then place a piece that is the target on d4. Move the piece anti-clockwise, ie e4-e5-e6-d6-c6-c5-c4. It will complete 1 full square. For each move of the piece (say a Rook), use a White piece (say Queen) and place it on a square such that it can attack both the Black King and the piece without being captured. Work out all the possible squares before moving the Black piece to the next square.
The main purpose is to associate the mind with the various attack patterns of each White piece against the King and another unprotected piece. This in turn trains the eye to identify threats such as pins, forks and skewers which form the main weapons in a junior's chess game.
Certainly, this may seem boring and tedious but then, isn't shooting free-throws at a basketball hoop and taking penalty shots? The secret is to hone the mind into identifying the threats (be it yours or your opponent's). To work out the full set of Concentric Square exercises, there are 4 attacking pieces (R,B,Q,N) and 3 shifting pieces (R,B,Q). That works out to 9 combinations and 1 for the Knight (which undoubtedly makes the same pattern be it the Black R,B or Q. By diligently doing the 10 exercises which can take about 1 hr, this is akin to practicing scales on the piano or violin or any other music instrument. Mastery and familiarity of the lines of attack will certainly raise the awareness of threats and improve the sight of the board for the chess player. For future details, its best to look for De La Maza's book "Rapid Chess Improvement" or look for his pioneer article "400 pts in 400 days" on the Net.