Allowing ELLs with low English proficiency to write in their native language can be extremely beneficial for a few reasons. First, writing in their L1 can give these students a sense of pride and accomplishment. If they believe they are capable writers, these students will then be more willing to write. Second, students who have low proficiency in English can often engage in more complex writing in their native language and can better express themselves than when they write in English. Last, with a strong literacy foundation in their first language, ELLs will be able to transfer that knowledge to their second language. This means allowing students to write in their L1 can build their writing skills in English (or other second language).
References
Uribe, M., & Nathenson-Mejía, S. (2008).Literacy essentials for English language learners: successful transitions. New York, NY: Teachers College Press.
Uribe, M., & Nathenson-Mejía, S. (2008).Literacy essentials for English language learners: successful transitions. New York, NY: Teachers College Press.