"Are there any assistive technologies appropriate for a 10-year-old?"
I've found several devices helpful for my fourth-grade students:
For organization: Try a hand-held planner with touch-screen technology, from Franklin.com.
For math:Scholastic.com/kids has a terrific page where students can practice their math. Or try MathPad Plus software (InfoUse.com/mathpadplus). Designed for grades three through five, it covers basic math operations, including fractions and decimals.
For writing: Kidspiration software (Inspiration.com) helps children organize their thoughts. It can help visual learners organize their notes in preparation for a test or group ideas to create an outline for a paper.
For note-taking: Portable Keyboards, such as the AlphaSmart 3000 (AlphaSmart.com), can hold up to 100 pages of text, which can be uploaded to a computer. They're wonderful for children who write slowly or illegibly.