I am a teacher but I don't teach children of that age. In my opinion 4 years old is much too young,certainly for an internet lesson. You can find someone who lives near you to teach him songs, but you can also just play him songs on the internet such as tudou or soku and find children's nursery rhymes. A formal lesson is not necessary before age 6 or 7, and will only cause him to dislike English when he begins to learn it at school.

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