As your child with CP is becoming a teenager, there are a couple of things you may want to think about.
Let me tell you about multimodal communication. We, as typical communicators, all use many different strategies. We use speech, gestures, facial expressions, technology, and no-tech solutions. As communicators, we all size up the situation based upon our communication partners, the context, the environment and then we choose to use the most effective communication strategy.
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.