Heuristic, imaginative and representational functions help a child to:

1. The last three of Halliday's functions are heuristic, imaginative and representational. 2. They all help the child to come to terms with his or her environment. 3. Expressing identity is the personal function. 4. Controlling others is the regulatory function, and greeting friends is the interactional function. **Why not the others:** Expressing identity is personal, controlling others is regulatory, and greeting friends is interactional, which belong to the first four functions. _Source: Wikipedia, "Michael Halliday", section "Studies in child language development" (revision 1371974860)_