How is education a social institution, especially public schools? Compare and contrast public schools and private schools. Please include a thesis, body paragraph, and conclusion.

Education is a social institution in that it teaches students how to become educated, informed, and hopefully independent thinking members of society. Both public and private schools do this with the difference being that private schools can impose whatever ideology or values they want to espouse. Public schools, especially those with a diverse student body in regards to socioeconomic status and race can be seen as a microcosm of the larger society.
Public schools act as a public institution by exposing and sometimes imposing the culture and values of society on students. Examples of this range from the curriculum that teachers are expected to teach, like the evolutionary theory instead of creationism, to students being allowed to use the locker room or restroom that they identify with. Depending on their ideology these things would not take place in a private school.
 
 

Education is a social institution in that, under ideal conditions, it teaches students how to be good citizens.  Students learn to get along with other people with different backgrounds and abilities.  This is helpful in the workplace as well as in society.  Students learn how to respect viewpoints even if they disagree with them.  Students are also encouraged to be involved in the social life of the school; outside of school, society works best when its citizens are involved in social and political activities.  
Private schools can differ from public schools because private schools usually focus on a group of students who are similar in some way, either through their family's income or their religion.  These schools, due to smaller class sizes, can attract highly qualified educators or educators of a similar religious background to their students.  While many private school graduates go on to prestigious universities and lucrative jobs, public school graduates, under ideal situations, get an access to American society that they would not otherwise get to experience outside of the classroom.  
I do not know if your instructor wants you to decide which school system is better—from my vantage point, public schools have an edge.  However, there are arguments that can be made for both systems.