There are numerous studies and books showing the effectiveness and value of Chess study and play on thinking and character development as well as the general importance of critical thinking and problem-solving abilities. Here is a good starting sample:
Benefits of Chess in the Classroom : Compiled by P.S. McDonald TOC [ PDF ]
Chess as a Way to Teach Thinking : Dianne Horgan Summary [ PDF ]
What Does Critical Thinking Mean? : Article by Terry Heick [ >> ]
Learning Outside the Classroom : UK Dept. of Ed. & Skills PDF [ >> ]
Psychology of Chess : Fernand Gobet (Book) [ >> ]
Chess Behind Bars : Carl Portman (Book) [ >> ]
A Pawn’s Journey : Elliott Neff (Book) [ >> ]
Toronto Catholic DSB Compilation of Note : PDF [ >> ]