In my experience, dual language immersion is one of the best ways kids can learn another language. I have two daughters who have participated in dual language programs for Spanish: one in elementary school, and the other in preschool and now pre-kindergarden - and they're both doing excelente! After reading the following article titled Districts diversify languages offered in dual immersion, I'm an even stronger supporter, as this approach can be an excellent option for ELL students.
While there is a great need for more world language acquisition overall in the US (we rate very poorly globally in world language skills), growing our ELL programs is a way to improve the education and lives of so many of the kids that are enrolled in the US public school system who are deficient in English and need this skill in order to improve their academic outlooks. This is an outcome that all US citizens should demand for our students, as there is a very real and tangible benefit we receive from high school graduates (and college enrollees) who have strong English language - and therefore academic - skills.