Conduct thorough research on your topic, using evidence from official publications and credible media reports. Interview experts in the subject if you can. Avoid expressing personal opinions, and attribute facts to reliable sources.
Compose a lead paragraph stating the question you are trying to answer with your essay. Explain the topic to the audience, and mention why it is an important issue.
Use language suitable to your audience. If they are children, choose appropriate vocabulary. Reserve advanced terminology for specialized audiences. The challenge in an investigative essay is to maintain the balance between clear and accurate speech.
Cite references for every fact you present, with the exception of experiments you conducted yourself. Mention the publication in which you found a fact or the person who revealed something to you in person.
Focus on the issue you are examining and not on the method of investigation. For example, in an essay about how high school coaches pick their players, concentrate on their criteria and considerations, not on how you contacted the coaches or how you recorded your conversation with them.
Answer the question you posed in the opening paragraph in a clear manner. The answer can be a succinct conclusive sentence or paragraph.