My teacher tells me I need greater focus on the question in my essays. How can I do this?

The best way to ensure a clear focus on the question throughout your essays is to plan beforehand. I like to make sure I have written 4-5 points on a scrap of paper, along with a link back to the question for each point, before I begin my essays, to ensure that I know what points I will make. It's even better if you can plan your conclusion before you begin to write your essay, as this ensures you have an end towards which you are writing in mind, which helps stop you from "waffling" throughout the essay. Once you have begun writing the essay, it is important to link back to the question each time you have made a point, to make it clear to your teacher (or the examiner) that you know why the point is relevant. You have to remember that examiners don't have a lot of time to mark each paper, so if you can clearly sign post each point you make and show why it is relevant, it will make your essay seem much more focused and concise. Also, if you find it harder to do this for some points and easier for others, it will show you which are your strongest and best points, and which maybe need a little more development.