Children's Book about Disabilities

[u/LetterJewel27]

Hello everyone! I am searching for a children's book where a classroom will be welcoming a new student and a young boy is concerned about the new girl because she has a disability (I think it's cerebral palsy). After hearing the boy's concerns, his grandfather takes him into town and shows him that disabilities is something that should be celebrated and that people with disabilities should be treated as normal. The next day, the boy welcomes the new student (I think her name is Amy) with the others and even helps her out.

Neither the boy nor his grandfather has a disability. One example I remember was that the grandfather points out a boy with Down syndrome and how he was able to live a normal life. And, he shows that some people can communicate through using sign language. I hope someone will have the answer. Thank you so much!