"How Handwriting Trains the Brain," in the Wall Street Journal, you can read about a "new" discovery we've known in the Montessori world for 100 years.
“The hands are the instruments of man’s intelligence.”
“The human hand allows the minds to reveal itself.”
“The mind and the hand are prepared separately for written language and follow different roads to the same goal.” Maria Montessori
Hence, the thousands of "hands-on" Montessori materials in a Montessori school.