Why I think chess is good to teach in schools
Chess really improves on yout concentration skills
Gives you the need to have a strategical view of the board to be able to play
An huge ammount of real life strategy such as the ones pointed out by Kasparov in "How chess imitates life" or even in that much less know book by that very badly know author Sun Tzu "The Art of War"
So we can say it prepares kids for the competitive world?
They are envolved in sport, so less time for drugs and other risk behavior by the pupils
If they are learning it as a group it helps them development relationships.
Its good for your memory altough not proved that chess players have a better memory then regular persons, its proven that the fact they are using the brain to remember moves keeps brain cells active and that prevents them from dying.
People who play chess are seen as "smarter" then the average by non playing people that as to be an advantage, it even help to insert chess in your resume!
Piece counting is an essential part of chess playing so you are always facing the need to do simple math, and it is well know that people don't improve on math by doing the hard exercices, but on repeating for an endless number of times simple math such as 2+3 or 8+7 etc, youl develop your brain in a way this tipe of thing is just automatic. So yes chess does improve your math skills.
Chess is fun and "pratical" in the sense kids do move the pieces and touch the board so they feel more connected to the game and the activity leaving them more interested.
There are more points about why chess is great to teach, ill let others say something about it now!