There has been some controversy in the American society about the bilingual programs, if they are effective or not to help the students considered LEP's (Limited English Proficiency). I would like to think that the criticism to Bilingual Programs would come from an educational point of view in benefit of the LEP students and not from biased feelings against immigrants. It is remarkable than most of the criticism doesn't come from educators but from politicians and even some wealthy people.
The theory of Bilingual Programs is simple on paper, but complicate when you work on it. Students who have literacy in their native language will learn English faster than LEP students who go to Immersion programs (100% English). In Dual Programs, students will have lesson in both languages at the same time, and in Inmersion programs students go to a regular English class, even if they have some extra support.
I remember a video I saw about trying to explain to American teachers how a student coming to the USA is going to feel in an immersion class: A Vietnamese speaker started to explain a lesson to the American teachers in Vietnamese... the teachers-students looked flabbergasted and disappointed, as they couldn't understand a word. This is how a foreign student is going to feel in their classrooms.
Learning English is not going to happen in one year, this is a myth, specially if you want the student to graduate High School and even attend college. The students acquire language in these steps:
1)Listening: from simple command to longer speeches.
2)Speaking: Slowly the students will start to talk. The will be embarrassed at first to talk in English, specially to teacher, but they will talk a lot later.
3)Reading: Students wil learn to read more and more in English, specially if they were good readers in their native tongue.
4)Writing: writing requires a lot of practice, even English speakers have a lot of spelling programs.
Actually there are some students whose parents speak English and they have problems with Reading and Writing.
The aim of any program is to be succesful, when somebody ask me about the Bililingual Program, I just look at my former students and I can conclude:
The students who were good in Spanish Math and Spanish Reading then they were good when they did the transition into English.
The students who were struggling when they were in Spanish Math and Reading, continued struggling when they were moved into English.
Some students who came from Mexico , Honduras or El Salvador when they were 8 or 9 years old and they were good students in their countries, they kept the good work in Texas and they learn English faster than the students who didn't know how to write their own language.
After some years of teaching, I can conclude that Bilingual and Dual Programs can work very well for most of the LEP children. It has been proved in several district in Texas. And here is an experience from the Hidalgo ISD in South Texas: No Excuses Education.