Every language has it’s own four basic skills which learners should master if they want to use language properly. It is the same when we learn our native language, first, we learn to listen, then to speak, then to read and at the end to write. We call it the four language skills.
When students learn the language they have to improve it with good grammar and rich vocabulary. It is assumed this is not the final purpose. The learner has to be able to use language but also he has to possess other skills and abilities which he will need. Sometimes learners are good at listening and speaking and we cannot say for them that they are good at English. It also happens that some learners do better in reading and writing than in listening and speaking, it means they can easily read and write, but they can hardly communicate. They are not able to express themselves with their own words. One teacher is not able to change the educational system but he can improve learning using methods which helps learners to enrich their knowledge. If learners want to use the language properly they have to master all the abilities of four skills.
When we learn the language we cannot separate these four skills. Learners can improve all four skills by training and participation.

Using a language in a communicative way is not considered as single skill. Receptive skills are listening and reading and productive skills are speaking and writing. Teachers cannot teach all four skills