How can you teach grammar communicatively?

By teaching it among conversations.

Teaching of English grammar must be started from the fundamental level. The classroom instructions, rather than being purely academical or theoretical, as far as possible must be practical oriented. Due weight age must be given to day to day usages in practical situations. Practical applications of rules and usages can be taught simply by integrating them with simple flawless communicative language....   

Teaching grammar communicatively can be achieved through inserting grammar in real-life situation examples: using grammar rules or patterns in situations taken from every day life. Teaching students authentic material in which grammar is used: dialogues, meetings, famous-person resume, carnavals, and so.     

Definitionally, grammar is a set of rules that govern language; its morphology and syntax.Teaching grammar "communicatively" is a student-teacher interaction process, the Socratic method of eliciting from the learner. It is the ability to communicate competently, thereby listening and responding appropriately to feedback. It is about applying the etiquette necessary for clear and simple communication which is geared towards passing a message. Grammar is basically concerned with  making meaning in the language through interpreting the message of the learner, expressing one's own, or negotiating when meaning is unclear. In brief,  communicative grammar in the communicative classroom is for learners to acquire language in the broadest of sense, thereby make meaning in their worldview.

Only in connection with speaking, listening and reading