What Are The Advantages Of Teaching A New Language To Young Learners?

The scientific reason would be that they are more able to learn a new language when they are still young.

Some personal reasons would be that sense of pride from helping mold a young mind and give them opportunities to excel in this ever expanding new world!

It is far easier to brain wash people when they are young.
In Africa, there are Ten year old that carry guns and fight wars. They are taught from birth to feel no pain because somebody realized it was easier to teach people when they were young.
Not trying to rain on your essay, I'm trying to give you a cross-piece here, so bear with me a sec.
Anyway, scientists are teaching parents to teach their babies other languages when they are young. It could be said that this has been tested to positive, or negative, effect in Africa. It works. You can teach people almost anything when they are young. They are much easier to mold.
You might use the African data as proof that this sort of technique works. I know that when I was in school, I liked to take the odd data and use it to drive my teachers nuts. It is scientific, and does correlate to your topic. If he gave you a bad grade, it would be because you outsmarted him.
Best way to cure a boring essay to turn it on its head, and think outside the box, eh?