It helps immensely if your students know how to read in Spanish and have content area knowledge in Spanish. Several skills can easily transfer from one language to the other. Research tells us that when your students are fully literate in Spanish, they will learn how to read in English more quickly and will transfer some of their literacy skills from Spanish to English.
ELLs do this particularly at the beginning stages of English proficiency; they lean on their Spanish knowledge to analyze patterns in English. It is very important to allow ELLs to transfer these skills and express themselves in the language they know best. They will rely less on this transfer as they become proficient and comfortable in English.
ELLs who are not literate in Spanish take longer to learn English. There are a number of factors that can help speed up their process of learning to read in English. These factors include how much time you spend on daily reading, the reading strategies you use to teach ELLs, how much reading is done at home, and how much help you receive from the ELLs' parents or guardians.