"The introduction should tell the reader what to expect in the essay. The introduction should make clear to the reader the focus of the essay, the scope of the research, in particular an indication of the sources to be used, and an insight into the line of argument to be taken." (IB EE guide. P.80)
Note: Do not write the introduction last. You should write it first and set the scene and focus for your essay. The introduction will also help you to outline the way in which you will approach the essay. However, you may come back to the introduction during and at the end of your essay to make modifications, as your essay may have changed from what you initially set out to do.
Key components of the introduction
Criterion A highlights the three key components that the introduction to you extended essay should include:
Communication of the broad topic of the essay and how your specific research topic fits in. You need to talk about why the topic and research is important and why your essay is worth reading and will contribute to research and discussion on the topic.
Identify your research question and make sure that it is clearly stated within the introduction and connected to the topic of study.
Provide your methodology and approach to that you will take to approaching the research question. This includes identifying the range and types of sources that you will use. You should explain how your approach to the essay is appropriate for the particular subject area that you have chosen for your essay, including why the sources that you will use are relevant and appropriate.
Specific guidance for writing the introduction
Each of the EE subject guides has a section about Criterion A: Focus and Method
You should read this section carefully before meeting with your supervisor to discuss writing your introduction. How you approach the introduction and explain the research methodology and approach to answering the research question will be different for each subject area.
Throughout the extended essay writing process you will be referred to the Academic Phrasebank from the University of Manchester in the UK. The phrasebank provides you with lots of writing ideas and phrases that can be used to make your writing more sophisticated and appropriate for an academic research paper. Check out their section about writing introductions.