We all have different towns and we all have different things that we do in the course of the day. It may be that the student is a great artist or a great writer. When it comes to assistive technology we have to think about what is going to give that student the ability to do what they love without having to see roadblocks and go, "I can't do that”. There are so many tools out there, whether it's a communication app, a video app, a math tool. With assistive technology you are not making the student into what you want them to be.
Every educator needs to make a decision about technology they need to put in place. They're not sure if they should put Option A in place or Option B in place. This can be particularly difficult in the world of disabilities because there might not always be a perfect answer. Teachers can look to this solution, using the least dangerous assumption to make good decisions about what technology might be best.
Upper limb therapies and interventions have been well studied in cerebral palsy. Different interventions that have good evidence are Constraint Induced Movement Therapy (CIMT) and Bimanual Therapy. CIMT has been shown to be successful in children with hemiplegic cerebral palsy (CP). CIMT uses a splint to physically constrain the uninvolved arm and encourage them to use the more involved or affected arm.
When you don't have enough evidence about a student's performance, assume they can do whatever you're asking them to do.