One of the most illustrative, helpful things we gave our DS's teachers were writing/drawing samples of "Healthy DS" versus "Exacerbation DS." The lightbulb seemed to literally go on for some of them when they saw his good, fully-legible math work at one period, as compared to the illegible scrawl for the same subject just a few months later. And I think it helped them know that this was not a kid who got "lazy" or "careless" overnight, or who had never mastered penmanship. The visual evidence was pretty irrefutable, and it helped them help us, too, since sometimes they would see the handwriting deterioration before we would see anything at home, and could alert us.
I like the idea of samples, but she has never had proficiency let alone mastery of handwriting. I am not sure her samples would make the point. But I do like that idea.