I am in a similar boat, My eight year old son will not write, He becomes frustrated and it just brings on melt-downs. My son's muscles in his hands that are used for fine motor skills are weaker than normal children. Does your ten year old write at all? My son is a good reader, with a good vocabulary, he just hates to write. I haven't heard of the word prediction app, what is that exactly? If your son also struggles with muscle weakness in his hands, I would recommend hand strengthening exercises like squeezing a squishy ball, or stringing beads, anything that will strengthen his hands and help with coordination. There are probably a lot of apps that might help some. I have tried the apps where they draw the letters and words with the tip of their finger on the screen, I think it has helped a little with the hand/eye coordination. I am also very curious if anyone else has any tips or advice. I have heard that penmanship is a common issue in the autism spectrum. There is computer software called Dragon voice recognition software,you speak and it types what you are saying. If your son wants to avoid writing all together that software might be helpful. In any case it might help his confidence level, he could "write" stories, or poems, or school reports, or whatever he needs, on his own,using the software.If he can already type the software wouldn't be very useful.