Well said! Unfortunately, the public in general seems to be relying more and more on letting the school system raise their children. Instead of leaving parents to teach things like common courtesy and personal hygiene, students often first come in contact with these topics in school.
You can place the world's best teacher in a classroom of students, but if the students don't pay attention or do their homework and the parents don't take an interest, then it is pretty safe to say that many students will not make it out of the class with good grades. Of course, this is more or less in regard to elementary schools.
Once you move on to junior high and high school, it is more up to the students to make sure they do well. In this stage of
education, I'd say that the blame would have to be split between the teachers and students- about 50/50. An algebra teacher who spends more time talking about the football team than making sure his or her students learn about logarithms and exponents is likely to have plenty of low-scoring students. On the flipside, subjects like history are easily self-taught and success there is more on the students' shoulders than the teacher's. One year, my history teacher was diagnosed with a severe case of cancer only a few weeks into the school year. The school system couldn't afford to hire a new full time teacher, so we had a parade of substitute teachers go through the class room all year long. It was an AP (Advanced Placement) class, so there was more on the line than just a grade; we took a test at the end of the year for college credit. Despite having no real teacher and no outline, many dedicated students scored well on the AP test and walked away with college credit for an American History course.
In university, the fingers point to students and professors, although the responsibility is ultimately the students'. You may not approve of a professor's teaching methods or perhaps you have a class taught by a foreign professor who can barely speak English. In the end, if you don't like it- drop it!
As the school system progresses, the responsibility seems to graduate from parents to students more than anything else. Aside from elementary school, I wouldn't point serious blame on anyone but the student. If someone wants to learn, they are going to learn. If they don't want to learn, they won't. You can't shove knowledge down a kid's throat- I don't care what kind of amazing teacher you are.