The bilingual classroom serves many purposes. At its roots, it encourages students to compare languages, learning more about each language in use, even when the subject matter strays from language arts. Perhaps even more important, a bilingual classroom gives equal opportunities to students who speak languages other than English as a primary language.
Judit Moschkovich, in her paper "Bilingual Mathematics Learners: How Views of Language, Bilingual Learners, and Mathematical Communication Impact Instruction," explains that a bilingual mathematics education should extend beyond vocabulary. Instead, students should learn how to express complex concepts, solve problems and describe patterns using both languages. When speaking to your students, hold entire conversations in one language on one day, with conversations in another language the next. In this way, you encourage students to think in both languages.
Science generally involves a great amount of reading and mastering new concepts. While some of these concepts may present difficulty for ESL students, especially when taught by a monolingual teacher, using pictures and visual representations of ideas can help mitigate some of the confusion. According to information from the University of California Los Angeles Language Materials Project, images "provide context for textual material" and provide "grounding and point of reference for teacher-led discussions." In both of these ways, pictures allow students to sidestep some of the difficulty of the second language.
For social studies, create a "global" classroom, where education is provided in at least two cultures. For a bilingual Spanish-English classroom, you may want to emphasize the relationships -- historic and current -- between Spanish speaking countries and English speaking countries. While some teachers may default to the often tumultuous relationship between Mexico and the United States, this dual education also could explore relationships between the United States and Spain, Cuba, and many Central and South American countries.