In most international schools, ESL students are excluded from the mainstream English/Language Arts class until they have reached a certain level of proficiency in the language. The English teacher, therefore, does not have to concern himself so much with modulating his language to ensure it is comprehensible to the students - unlike the science or math teacher, for example, who must ensure that the language of classroom instructions, homework, worksheets and tests is also comprehensible to beginning learners.
It is worth recalling at this point, however, that .. it can take learners of English as a second language as much as 5-7 years to catch up with their native-speaking peers as far as academic language proficiency is concerned. So the ESL students that have "made it" into the mainstream English class still need extra support.
Clearly, part of this extra support can be provided by the ESL teacher, who takes time in ESL class to allow students to ask questions about what they are finding difficult in the reading they have to do. The English teacher could also devote a little more time to ESL students in English class - for example, during the teacher-student discussions that form part of the frequently-used process writing/writing workshop approach. Another way to help ESL students is to use graphic organizers to enable them to understand plot or compare characters etc.
However, ESL students can be supported in more subtle but more fundamental ways. In particular, they benefit from themes that have relevance to their own lives and experiences, and from readings that are chosen from their own cultures, not only from the eurocentric canon. Indeed, all students in the class benefit from exposure to a diversity of cultural perspectives. The choice of which texts to study is therefore the critical issue for English teachers. For example, Much Ado about Nothing, which was read in grade 8 English at FIS, is a delightful play, and may well be appropriate for native English speakers of this age to study. It is debatable, however, whether the ESL students in the same class will derive equal benefit from several weeks studying a text that is linguistically extrememly demanding and that, for many, does not deal with themes of interest or importance to them.
Language as a theme of itself seems to be an excellent choice for the mainstream English class. Making students aware of the different ways that language can be used; having them compare idioms, proverbs and folktales or the various structural features of the languages represented in the classroom; discussing the hegemony of English as the world language: all these activities seem to be a very valuable use of English class time.
This is one issue that in my opinion needs special consideration. It is a clear goal of most mainstream English programs to enrich the vocabulary of the students at the various grade levels. The problem is that ESL students are starting from a much lower base. Whereas a well-read native English speaker in a grade 6 class may have an active vocabulary of 10,000 - 15,000 words, the newly-promoted ESL student may know 2,000-3,000 words. Clearly, the ESL student will not know the words in a text that are possibly new to the native speaker - e.g. sprouted, pasture or furrier - but should she be required to learn these for a test when she doesn't know complained, butcher or harvest*? I think she shouldn't, but this requires some flexibility (and extra work) on the part of the English or ESL teacher in order to ensure that she devotes time to learning the words that are important to her at this stage of her English development. (Of course, a better approach would be to allow students themselves to choose which words to learn for a test - but not all teachers have such freedom.)
* All these words are taken from the first two paragraphs of Zlateh the Goat (Singer, I.), the first story in the Prentice Hall Literature Aanthology (Copper), which is used in grade 6 English at FIS. The anthology has a good collection of readings from different cultures.