ESL stands for English as a Second Language, and generally English Language Learners (ELLs) are those people for whom English is not their primary language. ESL teachers work with ELLs to help them acquire fluency in English, both spoken and written. These teachers normally have special training in the field. Teachers in kindergarten through 12th grades usually hold credentials in ESL, and teachers at the community college level may have master's degrees in it.
One of the differences between a teacher of a foreign language and an ESL teacher is that most students taking the foreign language, at least in the US, share the common language of English. ELLs, on the other hand, don't necessarily share a common language. A teacher could be teaching adults or kids who speak a variety of languages, although various Asian languages and Spanish are most common.
Therefore, the one resource the ESL teacher usually doesn't have in the classroom is the ability to stop and explain things in a language common to all students. Though many teachers are fluent in several languages besides English, they generally aren't fluent in all of them, and the language background of an ESL class can be diverse. Therefore, explanations usually must be made in basic English, teaching the child or adult at first in simple ways with a lot of demonstration, pictures, and repetition, to understand English, to read it, and to speak it.
During training, a prospective ESL teacher learns some of the typical mistakes expected from certain language groups. For instance, many Asian languages don't pluralize word endings. Certain language groups don't need a specific order in sentences. Many aspects of the English language can be unfamiliar to the ELLs, including its alphabet. As students advance in English learning, and teaching grammar becomes a factor, focusing on common problems of the ESL student can be helpful.
In primary school settings, a teacher may focus on not only teaching kids how to speak English, but also how to read and write. Some ESL teachers are the primary teachers of ELL students, while others work in combination with standard primary teachers as auxiliary support. The goal is fluency for each student and an ability to quickly meet the same standards set for native English speakers.
Children tend to progress out of ESL classes into standard English classes, but the speed at which they do this depends a lot on their home environments. When English is not the primary home language, there are fewer opportunities to speak it. The teacher often encourages parents to take English classes too, which are frequently available for free at adult high schools or night schools. The more English a family can speak at home, the sooner a child will acquire fluency.
In the US, certain states have changed policies on how children are taught English, leading to fewer ESL teachers in the kindergarten through 12th grade setting. It was often the case in the past that the teacher taught not only English, but all subjects in the first few years of school, or that certain subjects were taught in the student's own language. This way, students could keep up with native English speakers in all subjects. Now, the goal in many states is to get the student immersed in regular class settings as quickly as possible, and many ESL programs have been dismantled, leading to fewer jobs in this field.