Learning a second language for a child is more practical and less academic.  It’s a matter of using the language through play and actions rather than studying the grammatical breakdown.  Children also have an advantage in terms of their stage of development.  In other words, a child is less concerned about getting their speech perfect and following the rules, so they are more open to and less fearful of mistakes.  Lastly, a child does have a definite advantage in terms of pronunciation.  In fact, research shows that children who begin learning a second language before adolescence will develop a more native-like pronunciation and are more likely to become fluent speakers.