At the beginning of the twenty-first century, proficiency in only one language is not enough for economic, societal, and educational success. The third approach was late-exit transitional bilingual education, where students received 40 percent of their instruction in the primary language and would continue to do so through sixth grade, regardless of whether they were reclassified as fluent-English-proficient.
If you are arguing against Prop 58, then I think you missed the point: We Californians, in our bias against Mexicans, put an end to dual-immersion bilingual classrooms in 1998, though research had repeatedly demonstrated it’s the most effective way to teach English to newcomers and help them achieve proficiency.
While students in bilingual education programs maintain their academic progress by receiving content-matter instruction in their native language, they may initially lag behind students in all-English programs on measures of English language proficiency.
The Bilingual Education Act was terminated in 2001 by new federal education policy, with the passage of No Child Left Behind by the U.S. Congress This law offers no support for native language learning, but rather emphasized accountability in English only, and mandates that all students, including ELLs, are tested yearly in English.
The other study uses scores from the California English Language Development Test, a richer measure of English proficiency 7 Because these scores were available beginning only in 2001, there are no pre-policy data; however, the broad intuition behind the empirical strategy is similar.