I agree that it's a broad topic. To make it interesting, why don't you take common misconceptions about the constitution. For example, many people believe that the constitution gives us rights that it does not. Privacy is not mentioned anywhere in the constitution, for example. There are a lot of things people think are true about the constituion that are simply misinterpretations.
I think that a presentation of the Constitution should focus on both the Preamble and the Bill of Rights. In my opinion these are two of the easier parts to talk about and present. I have seen students use poster board and write the Bill of Rights on the poster board and then use magazine clips and other pictures to show the rights in action.
If you're allowed to focus in on one section or segment of the Constitution, you could present on the Bill of Rights, and how each amendment was a specific response to a British policy or action, so that you can demonstrate you understand both what the amendments are, and how the Bill of Rights came to be.
The best way to do a presentation on the Constitution is to summarize the major ideas that are embodied in that document. You should look at the main goal of the Constitution and the ways in which it tries to achieve those goals.
The goal of the Constitution is to prevent the government from tyrannizing the people. It tries to accomplish this by setting out a system with
- Limited government -- the government can not simply do what it wants. There are things that it is specifically prohibited from doing.
- Separation of powers -- the government is split into three branches, each with its own function.
- Checks and balances -- each branch of government can interfere in the others' main functions.
By setting up such a system, the Constitution tries to keep government relatively weak so it cannot take away our freedoms.
There are many approaches you can take to this, and I think that you might need to reflect upon which aspects of the Constitution are the most appealing to you. For example, I think that you could render a very strong presentation on what you consider to be the "Top 5 List of Important Amendments." It would really be fascinating to engage in a discussion of the most essential amendments or the criteria used to determine "importance" in Constitutional amendments. You could also give a presentation on the Preamble, the introduction to the document that outlines its goals. Perhaps, analyzing the most important part of the Preamble or the part that is the most disrespected today. Finally, you could deliver a presentation on "Influences on the Constitution," something that assesses the thinkers on the world stage that played important and formative roles in the Constitution. In any presentation about the Constitution, it is important to find some part of it that "speaks" to you today and something upon which you can find relevancy in connecting to an audience.