People think it’s so easy for children to learn a second (or third) language and in some ways it is.  But only if they have a real stake in learning it.  The biggest challenge for parents who want to raise a bilingual child is to make the child WANT to learn it.  There’s a common saying that “you can lead a horse to water but you can’t make him drink.”  You can provide the necessary environment, but the presence alone of “the water” is not enough.  On the other hand, if the child is “thirsty” for the language, you can’t keep him from drinking it in.  If there is no water available, children will look for water until they find it.