Have newcomers read in their home language as much as possible.
Research shows that “there is a strong transfer between a student’s primary language and the development of second language literacy” (Goldenberg, 2010).
In school and at home, students should be reading books in their first language, bilingual books (written in both their L1 and L2), and English books at their level (and hopefully age-appropriate). Provide Spanish-speaking ELLs with a Spanish version of the textbooks or workbooks you are using, if available. There is a Spanish edition of Go Math. Use it! Test Spanish-speaking newcomers with the translated practice exams included in the SE and TE. Remember, you're not testing their language skills, you're testing their math skills. On the state exam, they will be provided with a translation. No need for unnecessary frustration.
As I previously explained, allow them read in their own language, but also push them to start reading English with a Level A book. They will need to read the book with you first to learn how to pronounce the words. Point to the pictures when you read the corresponding word. Have them repeat the words after you read them. Read the book again with them. Then, have them read it to you on their own.
Here is an excellent article about 6 things you should NEVER say to your ELLs: