It has been proven with both scientific and anecdotal evidence that the younger you start a student on a second language, the more likely they will become fluent in both languages. In the United States, we are facing a future where bilingualism will be preferable in the working world. Start them as young as possible on English as a first language and Spanish as a second.
It is widely believed and accepted that it is far easier to learn a new language as a child. For this reason it is much more beneficial to teach young students in two languages. I believe this has been a huge failure in American education because we still fail to even offer this option.
A young child is very receptive to learning language because he or she is still learning the native tongue of the household and culture. So it would behoove the educational system in the United States to have classes in to languages so that every person can speak and understand at least that many.
It is a great thing to teach young students two languages. Firstly, it's easier to absorb a language when you're that young. And, secondly, it is a good way to broaden a child's horizons and give them a better set up in the future. It teaches you to really think.
No it is not beneficial to teach young students two different languages they can get so used to it that they don't know a lot of English. Another reason is because there parents might not want them to. The last reason is because you may not be able to talk it to any body. For this reason it is not beneficial to teach two languages.