How do I write an effective introduction and conclusion in my essay?

Introductions and conclusions are vital in essays, however they both serve different purposes. The introduction is there to set the scene. I would start off by writing a couple of sentences giving some context. For the higher grades, directly link the themes in the essay question to the context rather than writing some general\vague sentences. Then answer the essay question by simply stating your opinion. There is no need to explain your opinion at this point, the main body of your essay should do that. To finish your introduction, outline the main points in your argument in chronological order. If you want, you can state which point you find most convincing. Try and keep your introduction and short and succinct as possible.
The conclusion is there to round off your essay. Compare all of your arguments against each other. Which one was the least convincing? Why? Compare this against the most convincing argument and explain why it is the best point. This will show the examiner you can evaluate. Evaluation is a key skill needed to gain the higher marks. Weighing up all of your points against each other will explain the answer to your essay. To end your conclusion, concisely answer the essay question in one sentence. Remember no new points should be added in your conclusion!