My 10 year old son with motor dyspraxia, SPD and hypotonia was very similar at your son's age.
My son didn't get OT in Kindergarten, so we had to figure out what worked best by trial and error. By 5 1/2 he was also able to write his letters and numbers but sometimes they were backwards, his writing was sloppy and if he didn't use lined paper the letters were different sizes and he had trouble leaving enough spaces in between words. His writing was legible, but barely, and he couldn't write very much at all before his hands hurt.
When he turned six, I started homeschooling him because the school recommended it. They said they had never seen a kid like him before and didn't know what to do with him, so I was left to figure out how to be a teacher and an OT without any training at all. All I had was message boards like teachers.net and other gifted boards where I sometimes asked questions.
Since I didn't have a clue what I was doing, I could only use trial and error. I saw very quickly that it didn't do my son or me any good to insist that he write as much as other kids because once he was to the point where his hands hurt and he was unhappy, he wasn't learning a thing and my blood pressure went up and we were both miserable. Short handwriting practice sessions helped, but he still had problems with spacing and occasional reversals. So at age 7, I took him to a developmental pediatrician, an OT, and an educational psychologist who tested his spelling ability by having him write the words which I thought was kind of crazy considering the handwriting issues. Once his hands got tired, he stopped writing and this was supposed to test his spelling ability? The "experts" just told me to use Handwriting without Tears. Since he had already learned how to write one way, he was not happy about having to learn a different way so we both thought the name "Handwriting without Tears" was a misnomer. He ended up writing the letters in whatever way was easiest for him. My only rule was that it had to be legible. His spacing did get better after using HWT and at age 9 the OT thought his handwriting (printing only) was good enough that she did not work with him on this. I think she called it low normal. He still has the problem with his hands getting tired after writing a few sentences, so he types almost everything now. He took his time learning cursive because we concentrated on printing since that is what most of the other Cub Scouts were using. When we used Handwriting without Tears for cursive writing, we found that once he was through with the books and tried to use regular paper instead of their special paper, he had some trouble with this, so I am lightly drawing lines in between the lines on regular notebook paper until he gets used to the regular paper.
One of the hardest things for us to deal with was multi-digit multiplication and division. At seven he had a terrible time keeping columns straight so I had to act as his scribe. At 10, this isn't as much of a problem, but hands getting tired is still a problem, so he only does a maximum of 4 or 5 math problems a day.
Recently, we started taking one day a week to just "get lost in Wikipedia Land" as my son likes to call it. We don't do any math or cursive handwriting practice on those days and we really enjoy this. Maybe it will take my son longer to become proficient at cursive handwriting but I feel like we both need these less stressful days. He learns more on Monday without the stress of working on motor skill dependent activities than any other day of the week. I am so glad that we have the freedom as homeschoolers to do this, to be able to learn and not be held back by a mild disability.
