If you are an educator who has been tasked with teaching essay writing to high schoolers, do not lose hope. There are resources out there at your disposal. For many (not all) high school students, essay writing can be quite an arduous task, and if it is not properly taught then the student will suffer in the long run.
There are many ways that you can approach the task of teaching essay writing. The main thing that you should do is keep an open mind. While you should not ignore the basic rules of essay writing, you should also come up with your own approach to making the teaching process and the simultaneous learning process productive for both you and the students in your class.
Usually high school English classes require a basic five paragraph essay as the standard for testing a student's writing ability. The best way for you as an educator to convey this is by breaking the paragraphs up into smaller parts. Students will better be able to digest the brunt of the lesson when you break each paragraph up. In doing this you can actually put together a mini outline as a means of illustrating to your secondary students how to effectively write an essay.
It is not unusual for students to feel intimidated by having to write an essay. That is why it is up to you as the educator to put their inquisitive minds at ease.
The key to teaching secondary school students about writing is to ease their tension at all costs. So initially, the more tools that you provide them with, the better off they will inevitably be.
Let's say (for the sake of illustration) that you are reviewing the book The Count of Monte Cristo; you can draw a few strong statements from that book, such as "revenge can be bittersweet."
As the educator you can either choose to expand upon that phrase or just leave it as is and allow the students to draw examples from the book in support of or against the phrase. Revenge is a pinnacle theme in that particular book and as you illustrate the idea your outline will first reflect the thesis being "revenge is bittersweet" and the supporting paragraphs that are either in favor of or against the thesis.
As long as you encourage creativity and integrity in the classroom, your secondary students will thrive when writing their essays.