An essay usually presents the author's personal interpretation of the topic. This is your opportunity to select some aspect or aspects of the London Olympics that you particularly enjoyed or found memorable for some reason, and explain why these were noteworthy.
Start your essay by identifying the part(s) of the Olympics that you will be describing and briefly explain why you chose those events. If you plan to describe particular athletes, use the body of your essay to give details of how they prepared for the Olympics, how their competition events went, and what you learned by watching them. If you decide to focus on a specific sport, you might tell about the types of equipment used and explain how the Olympic rules for the sport differ from the rules you follow for that sport in a non-Olympic setting.
Conclude your essay with a summarization of what you most enjoyed, what you learned, and your predictions for what willl happen in Rio in 2016.