Two languages are apparently better than one. A number of recent studies have concluded that bilingualism - the regular, high-level use of more than one language - can lead to improved early brain development. Researchers aren't sure exactly why bilingualism leads to stronger brains, but they theorize that switching from one language to another, and regularly selecting which one is right for each situation, is a kind of mental work-out.
Young brains are more receptive to subtle differences in grammar and sound perception, making them more able to detect and understand speech patterns in new languages. Kids' gray matter is also more malleable, so that several languages can inhabit the same physical part of the brain. Studies have shown bilingual people have denser gray matter than the monolingual.
As well as the benefits, there are some minor drawbacks to teaching kids another language or languages: word retrieval is apparently milliseconds slower in bilingual kids than monolingual ones, and overall vocabulary in the original language is usually somewhat smaller. Still, Canadians know that bilingualism can lead to both clever children and a great country.