I recently had a meeting with my son's teacher. In the meeting she suggested that I stop teaching him arabic and focus only on English. Arabic is a big part of our family.
She said only with reading and writing. She said to wait until he reaches first grade. We recently returned to America. So my question is should I take this advice or should I continue in teaching my son how to read and write Arabic?
I understand you to be saying that you are a native Arabic speaker living in America. Is that correct? In that case I think this teacher has given you extremely bad advice. All professional linguists recognise the great value of learning as many languages as possible when young. Children are the best learners of languages. I assume (correct me if I am wrong) that English is not your own first language. In that case it is much better for you to speak to your child all the time in Arabic rather than in your perhaps less than perfect English. Your child will be exposed to English in school, from his friends, from television and so forth. This way he will grow up in the very privileged position of speaking two languages perfectly.
Remember the famous line: "Never Let Schooling Interfere With Your Education".
Teaching your son a second language will actually make him smarter and expose him to different cultural views.
Personally, I have learnt Arabic, Zulu and Afrikaans as secondary languages during my schooling.
Even though I don't speak those languages as fluently as a native, I can still read and write in all of them.
I am sure that he will be grateful to you when he grows he up.