This comes from NPR today: http://www.npr.org/blogs/ed/2014/08/06/336361277/scientists-say-childs-play-helps-build-a-better-brain
Apparently there will be more on the subject this week—from 8/6/2014
As stated herein before, we should leave forming letters and numerals until kids are ready. Their hands and fingers need to develop so they can hold a pencil in a relaxed manner when it’s time to write. That comes from play. Scribble, yes. And provide any other stuff that leads to picking it up, holding, moving, pushing or squeezing it with thumb and index finger.