-The teaching and learning of writing should link theory and classroom practice-. 
And in considering the above statement, you are expected to explain why writing is important, and how to teach it effectively. 
As always, as with any assignment, it is important to begin with an analysis of the topic. So, you might need to think about the following: 
1. 1. The essay as a form of writing 
2. 2. The teaching of writing 
3. 3. The learning of writing 
4. 4. Theories about teaching and learning of writing 
5. 5. Classroom practices for the teaching and learning of writing 
6. 6. Effective practices for the teaching of writing in particular contexts 
7. 7. The importance of teaching writing 
8. 8. The rubric for the assessment 
9. And you need to fit all of this in 1500 words. 
So, it would be good to begin early. The process conference approach to the teaching and learning of writing that was dominant in the late 70s though to the middle 90s was based on the belief that all children could write if they were given: choice about and "ownership" of their writing; scaffolding in the form of a "process" to be followed that would result in a "product" that they could "publish"; the opportunity to replicate the process that "real writers" go through to produce "real writing"; and teaching that drew out the genius in each child. 
The key theorists for this approach were people like: 
* James Britton. (1972). Language and learning, Harmondsworth: Penguin Books; 
* Donald Graves. (1983). Writing: teachers and children at work, Exeter, New Hampshire: Heinemann; 
* Lucy McCormick Calkins. (1983). Lessons from a child: The teaching and learning of writing, Portsmouth, NH: Heinemann; (1991) Living between the lines, Portsmouth, NH: Heinemann; http://educationnext.org/the-lucy-calkins-project/, 
* Robert Walshe. (1981) Every child can write: Learning and teaching written expression in the 1980s, Rozelle, N.S.W: Primary English Teaching Association); 
* Jan Turbill. (1982) No better way to teach writing, Rozelle, NSW: PETA; (1983) Now we want to write, Rozelle, NSW: PETA); 
* Marie Clay. (1987) Writing begins at home: Preparing children for writing before they go to school. Auckland, N.Z.: Heinemann, 1987. 
This approach, which contends that we learn to write by writing, is alive and well in many places today, e.g., http://educationnext.org/the-lucy-calkins-project/. 
It is quite a different theory from that which underpinned my early learning of writing that I described in my introductory welcome post. I do not want to place too much emphasis on the process-conference approach, which dominated the teaching and learning of writing in the 1980s and 1990s. It was supplanted to some extent by the genre theories of teaching writing in the 1990s, which in turn were challenged by theories and practices that were affected by sociological and technological changes since the 1990s, but it still has some value today - especially for you as you launch into your first assessment. 
I merely want to draw your attention to the fact that writing a good essay necessarily involves a process (ideas, research, draft, reflection or conference, revision, reflection or conference, editing, publication of the product or posting to Turnitin, response or marking). You need to start the essay early if it is to be worthwhile. You can use mindmaps or explosion charts to get you going. You can use a KWL chart to structure your writing process. You should use the DB Forum on the First Assessment and any other opportunities you can find to confer about your developing essay. 
Because essay writing is a process, you may need to write a first paragraph to get you going, And you will need to write an entirely new first paragraph when you are almost finished the essay, in order to state your thesis and delineate the structure of your essay for your reader/marker. Few people can see what the introduction will be like till they have almost finished the writing. So please be aware of your own processes and of the need to produce a product that can be read easily. 
I look forward to your posts on this first assessment.