As I point out in my new book, A Government of Wolves: The Emerging American Police State, there are several methods for controlling a population. You can intimidate the citizenry into obedience through force, relying on military strength and weaponry such as SWAT team raids, militarized police, and a vast array of lethal and nonlethal weapons. You can manipulate them into marching in lockstep with your dictates through the use of propaganda and carefully timed fear tactics about threats to their safety, whether through the phantom menace of terrorist attacks or shooting sprees by solitary gunmen. Or you can indoctrinate them into compliance from an early age through the schools, discouraging them from thinking for themselves while rewarding them for regurgitating whatever the government, through its so-called educational standards, dictates they should be taught.
Those who founded America believed that an educated citizenry knowledgeable about their rights was the surest means of preserving freedom. If so, then the inverse should also hold true: that the surest way for a government to maintain its power and keep the citizenry in line is by rendering them ignorant of their rights and unable to think for themselves.