Provide an overview or background of aviation/airport security (a brief history from where we were to where we are today).
State the problem or issue that needs to be addressed. This should be fairly straightforward since you were given a very specific case to write on - pros and cons of TSA vs. private security.
State why this problem needs to be addressed, why is it important, what will happen if allowed to continue, and so forth.
List one thing that has been attempted to address the problem under point II.
List the advantage of that attempt.
List the disadvantage of that attempt.