yes, thanks. Here is another one :
well.blogs.nytimes.com/2016/06/20/why-handwriting-is-still-essential-in-the-keyboard-age/
Does not help lucyin thesky and her grandson, though. I would ask for a meeting with teacher to discuss how, as a team, school, parents + grandparents- you could help him improve and help with confidence too. My grandson is left-handed and not a neat writer, but it does not seem to bother him.
If that fails, and you can afford it- perhaps ask a local tutor to help for a few weeks and get him some specific excercises?
Doctors and how they come across

