Editing Language immersion (section)

== Issues ==
* The design of  exposure time for each language
The first issue is the allocation of time given to each language. Educators have thought that more exposure to the students' L2 will lead to greater L2 proficiency,<ref>Antoniou, M., Wong, P. M., & Suiping, W. (2015). The Effect of Intensified Language Exposure on Accommodating Talker Variability. Journal of Speech, Language & Hearing Research, 58(3), 722-727. {{doi|10.1044/2015_JSLHR-S-14-0259}}</ref> but it is difficult for students to learn abstract and complex concepts only by L2. Different types of language immersion schools allocate different time to each language, but there is still no evidence to prove that any particular way is best.<ref>Duncan, T. S., & Paradis, J. (2016). English language learners' nonword repetition performance: the influence of age, L2 vocabulary size, length of L2 exposure, and L1 phonology. Journal of Speech, Language, and Hearing Research, (1), 39. {{doi|10.1044/2015_JSLHR-L-14-0020}}</ref>

* The challenges of curriculum, instruction, and instructors

In the United States, state and local government only provide curriculum for teaching students in only one language. There is no standard curriculum for language-immersion schools.<ref>Armstrong, D. G. (2003). Curriculum today. Upper Saddle River, N.J.: Merrill Prentice Hall, c2003.</ref>

Besides, the states do not provide assistance in how to promote biliteracy. Bilingual teaching has been too little researched. The report of the Council of the Great City Schools in 2013 has shown that half of the city schools lack professional bilingual teaching instructors.<ref>Freeman, Y. S., & Freeman, D. E. (2015). Research on Preparing Inservice Teachers to Work Effectively with Emergent Bilinguals. Bingley, UK: Emerald Group Publishing Limited. Research on Preparing Inservice Teachers to Work Effectively with Emergent Bilinguals. Bingley, UK: Emerald Group Publishing Limited.</ref>

* Bilingual proficiency

There are challenges to developing high proficiency in two languages or balance in bilingual skills, especially for early immersion students. Children complete the development of their first language by the age 7, and L1 and L2 affect each other during language development.<ref>Eckman, F. R. (1995). Second language acquisition : theory and pedagogy. Mahwah, N.J. : L. Erlbaum Associates, 1995.</ref> High levels of bilingual proficiency are hard to achieve. Students with more exposure are better. For second-language immersion schools, immersion too early in a second language leads students to fail to be proficient in their first language.