re: Chess Board for my Son's Birthday

BB1.... wood expansion and contraction happens across the grain with the width. Running with the grain sees very little to none. With small pieces, especially with each glued to the other the change is fairly negligible. With the frame there's nothing to worry about. There's simply not enough width and cross section to pose an issue. I try to orient the squares so one grain looks like it runs continuously with the next but it's hard to do. 
It's was a fun project that I learned from and can benefit from with my next one.