ESP is English for Specific Purposes. It is basically the next step up from functional English. With functional English, we teach the basic functional skills. With ESP, we teach the very specific functional skills of specific areas, such as business English, technical English (eg engineering), scientific English, medical English and many others.

If you are asked to teach, or would like to specialize in teaching, one of these ESP areas then you teach it as you would teach any other aspect of functional English. The target is to improve the function, not make them generally better English users. All vocabulary or all grammar structures may or may not be needed; you only introduce what is necessary for the function.

It certainly helps if you have some prior knowledge of the subject you are going to teach, but it is not necessary. You have to try and remember you are not meant to be teaching them, for example, law. You are helping them transfer their existing knowledge of law from one language to English. They are the law experts, you are the teaching expert. Continuing with the example of law, if you had to teach contract law you would find the relevant language book that specialized in teaching this subject and you would teach from it using exactly the same teaching methodology as if you were teaching fruit. You would have to do a lot more preparation to make sure that you can explain the terminology by first having to understand it yourself, but other than that the process is exactly the same.

Most of the time, schools and bosses don’t ask new teachers to teach ESP. If they do, you shouldn’t be paralysed with fear. It’s the same as teaching Present Perfect Continuous. Many of you will not quite understand how we use it, so you will prepare for the lesson.