My school ha been teaching us a second language since Pre-k. The teach this language more and more as we get older because it is so important to us. In middle school, we have 4 classes that involve this language. The language, by the way is Hebrew. But besides Hebrew it is important to know languages that are often spoken near where you live.
There are many studies that report the advantages of being fluent, or even mildly fluent, in more than one language, some of which include brain growth, increased memory power, and a longer attention span. Additionally, Americans are generally ethnocentric, and one way to escape this stereotype would be to branch out and learn another language. English is a finite language- there are some ideas and phrases in English that could be expressed much better in other languages. I myself have learned two additional languages, and it is truly an enriching experience. There is a tremendously enriching culture outside of the English-American language that so many Americans would do well to discover! Practically speaking, it is not important to learn another language- you can get by with just English in almost any developed country- but on all other fronts, it would be a pity not to do so.
English is being taught as a second language in almost all modernized nations. The point of learning another language is to do business. You will not need to learn an African dialect, or Spanish, or Russian, as there is no business to be done there. South America entirely is too corrupt, Russia has an almost worthless currency with all these U.N. sanctions, and there is no reason to do anything in Africa. French is an international language, but the nation itself hates the private sector, so no need to do business there. All those regulations hurt the private jobs as well as the extremely high tax rate. Germany is Europe's largest economy, but most Germans speak English already. Japan is another world economy, but it is easier for the Japanese to learn English then for Americans to learn Japanese. Everyone speaks or will speak English in the future, no reason to learn anything but English. Personally, I find some languages to be rather beautiful and help linguistically, so I learn French and might learn Russian in the future, but there is no real need to learn anything else.
Yes, US children should have the option to learn another language. I encourage anyone who wants to learn another language, however living in America I do not believe that another language is necessary. For an one who wants to live in the United States it should be mandatory that you speak English and adapt to this country.