School, as America recognizes it, is important in creating a literate and productive society. Empowering the populace with the ability to read and providing them with core knowledge in various content areas helps them to be more effective members of society. School sharpens the abilities of critical thinking, examining multiple perspectives, and meeting deadlines, all of which are important for a populace.

On a very practical level, schools also provide a means of meeting the needs of society's most vulnerable children. There are children across America who arrive at schools with inadequate medical care and undiagnosed medical conditions. Teachers and counselors are trained to recognize warning signs that children may need additional support, from glasses to hearing aids to life-saving medication and therapies.

Schools also network with community organizations to provide help for students whose parents may not be able to afford needed medical assistance. Schools provide free and reduced breakfast and lunches to students in need, and many have developed "backpack programs" to send food home with hungry children on the weekends and through the summer months. In this way, schools are a safety net for students.

Schools also provide students with a means of interacting with others who are different from themselves. A student's family and even neighborhood may look fairly uniform in many ways. Schools provide a meaningful context for students to work others who are different. Students of various races, ethnicities, religions, physical abilities, and mental abilities share space together each day and learn to work toward common goals and to engage in meaningful conversations. This is helpful as society works to be conscientious of others' needs.

School is important because it is a tool to help prepare us for life.  Not only can we learn the basic skills to read, write, and do arithmetic but we can learn about peoples, places, and nature.  School prepares us to be the future caretakers of this planet when our parents are dead and gone, and it gives us the knowledge to pass on to our children and the future generation.  As such, we should appreciate the great gift we have when we're able to attend school.

I have to agree that "Life is a school." We learn everyday, whether or not we are in a classroom. School is important because it gives people the building blocks necessary to do many things: critically analyze, read, perform mathematical functions, write, etc. Without these building blocks people would not understand some of the things necessary in everyday life.

School also provides exposure to activities, ideas, and fields of knowledge that you might never encounter otherwise. While some of these experiences strike students as being a waste of time and effort, others may open up whole new areas of interest in a person's life. The discipline of working through a body of knowledge that doesn't particularly appeal to one's personal tastes also develops self-discipline and can lead to a (sometimes perverse) sense of self-satisfaction - "I didn't like doing it, but I made it through the course!"

I agree with post #4, if nothing else, school is invaluable just for the socialization aspect.  There are many life lessons to be learned in the classroom that will benefit students as adults:  time management, a strong work ethic, collaboration, multi-tasking, and self-discipline.

School introduces you to other points of view, which is necessary to learn tolerance and empathy.  School provides you with exposure to diversity in culture and religion, something we also need to develop tolerance and empathy.  School provides you with a formal structure that real life learning does not, and that structure helps you to learn self-discipline.  One of my father's favorite sayings when we were growing up was, "School teaches you to do the things that have to be done, when they have to be done."  The trick, in my opinion, is to internalize the lessons of school without losing one's creativity and joy in learning.  Some schools are more effective at helping with this than others. 

Outside of all the things that previous posts have said, school teaches you how to get by in the world.  It teaches you how to deal with bosses (teachers) that you may or may not really like.  It teaches you to cope with people that you have to work with (classmates) that may annoy you.  Basically, academics aside, it teaches you a lot of the social skills that you will need for your life.

Life is a school; we never stop learning.  The 12-20 years that we spend in a classroom are only part of the learning process that begins the moment we are born and ends when we die.  And to some, who believe in a life after death, our learning continues on indefinitely.

According to the http://www.thefreedictionary.com/school, the definition of the verb "to school" is

To train or discipline; to educate in or as if in an institution of learning.

And from http://dictionary.reference.com/browse/learning, learning is defined as

the act or process of acquiring knowledge or skill.

That being the case, our schooling begins the second we draw our first breath of life as a tiny, newborn infant.  From Day 1 in this life, we are being taught.  By the time we are old enough to go to an institution of learning, we will already have 5-6 years learning experience.  Picture those 5-6 years in your mind. Picture the tremendous progress from helpless babe in arms, that can only communciate through crying and has to have everything done for them to the chattering, active, independent boy or girl our baby has grown into.  Not only has the body increased in size, but the brain capacity has multiplied astronomically.  In five short years, your child has learned to talk, walk, and reason. 

At age five or six, we send our children off to school where they remain for about twelve years, ultimately graduating from high school at about age eighteen.  Many go on to higher institutions for 2, 4, 6, or 8 years, getting rewarded with college degrees in preparation for their chosen careers.  That is the importance of schools-to help prepare us to better live our lives.  But does the learning stop there?  It does not.

Throughout our lives we are constantly learning new things and will never stop learning new things.  Our formal years of schooling may be over with, but the learning continues on until we die.