That's not the English they are familiar with. Nevertheless they learn the language in a very short time -if the proper techniques are used and if the students have a real commitment. They improve their already home-acquired English language skills. 1l-l8 percentile grades in their Mother tongue. Bettering their income.
Writing is a secondary manifestation and ultimately speech-based.
Understanding the spoken language is taught more efficiently before oral production and is indeed a step toward production. We assume that the English student already knows how to write and read some English to a certain degree. One fixes the speech patterns through repetition. Learning a language is a conscious and automatic process at the same time. Languages are learned not taught.