Learning to write is a process. Hand writing is a slow and intense step, requiring both intellectual and physical efforts. I would guess the "joined up" part is

Learning to write is a process. Hand writing is a slow and intense step, requiring both intellectual and physical efforts. I would guess the "joined up" part is about "flow" and aesthetics. I am not sure whether the education I received formed the appreciation I have of this process or if it was something universally well thought, but even today, writing helps me thinking. Walking, running, doing handwork too. Moreover, I still find handwriting a thing of beauty, may it be notebooks or artistic calligraphy.