Watch this video by Dr. Steve Hughes, Professor of Neuro-psychology at The University of Minnesota.
The first 6:30 minutes are an elementary Geometry lesson.
The rest gets into the neuro-psychology, and his family's history with Montessori.
Included are lots of images and explanations for how Dr. Montessori observed what technology is now PROVING about how children learn - including those with dyslexia and other "disorders".
Writing grasp starts at 32:00.