Weight, height and body composition are important indicators for development. The tools used to measure these can be different for children with cerebral palsy.
Children with cerebral palsy (CP) often grow poorly and assessment of growth in this population is further complicated by two main difficulties. Firstly, children may have joint contractures, muscular weakness, scoliosis, and/or involuntary movements that make standing or lying straight difficult, if not impossible.
A speech language pathologist is someone who is trained in working with kids and adults. Everything from working with articulation errors and correcting things to what I do, which is working with people with profound physical impairments and getting them augmentative communication strategies.
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.
When you don't have enough evidence about a student's performance, assume they can do whatever you're asking them to do.