Interview the school professionals, teachers, coaches, etc.
Walk and talk.
Read the local papers or call the papers and ask if they have done any stories about the special needs in schools and who they spoke to.
Of course choosing a local real estate pro can help you save a lot of time.
(Not me, I'm on the Cape, but I can help you choose a local pro if you need help.)
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I would reach out to those groups to discuss your child's needs and see if they know of similar kids getting services. There is also The Learning Center in Framingham, a well known and innovative school for the deaf and hard of hearing.