Write the cover page to inform your audience of the topic of your experiment. The cover page traditionally has your name, the name of any research partners, your class or lab information and the date. If your paper is not for a course, then it is traditional to have your contact information and the name of the organization that you are affiliated with on the document.
On the following page, write a 150 to 300 word abstract that summarizes your experiment. You should focus on what your objective was and how you were going to demonstrate your objective. Many abstracts also include a brief description of the results of the experiment.
Develop the background and introductions. This section will define the terms that you use in the paper, explain what other researchers have found on the topic and place your experiment in context. In general, you want to have enough information in the introduction so the audience has all of the information needed to interpret the results and understand the findings, but no unnecessary information.
State your hypothesis, or what you are testing. This may be called a research question in some fields, but the idea is the same. It is a general statement that you are using your experiment to prove or disprove.
Describe the procedures or methodology. Explain exactly what you did, what tools you used, and what controls were in place. It is often helpful to include diagrams and graphs for this section. Additionally, many audiences do not require a step-by-step format, so the objective is to have enough information that the audience can replicate your experiment, but you can omit any obvious details or stages.
Write your results and the analysis of your results. Depending on your discipline, it is often typical to present your findings in a table and then to discuss the implications of those findings in the text. However, if that format does not fit your findings, presenting the information through a narrative is perfectly acceptable, as long as it is clear.
Finalize your report with any possible errors from your experiment, any changes you would recommend be made in the future and your conclusions. This section is designed to explain away any reasons why your experiment was not perfect and allow you to contextualize your findings. It is normally a fairly short and concise section that summarizes the findings, limitations and importance of your work.