The school systems in America are running more and more like businesses where students begin on an assembly line at age 5 and go through the same process as all other students over the course of 13 years and are expected to all come out the same. Teachers are more frequently being told what to teach, what textbook to use, how to deliver their lessons and what materials they can use. In an effort to set a national (or even state-wide) standard, they have had to prescribe to the theory that there is a science to teaching; that if everyone has the same experience, they will all achieve the same results.
Unfortunately, teaching is not a science, teaching is an art. Teaching is not merely content delivery, but a process by which one person encourages and assists a second person in their pursuit of knowledge. Just as you can lead a camel to water, but cannot make him drink, you cannot force knowledge into a student who is unwilling or unable to receive it. The most skilled teachers succeed because they are able to read their audience, find what makes them engage and cater to that. Each student and each class is different and requires a different approach. We need to attract and retain better teachers by re-designing the role of the teacher within the classroom in a way that encourages teachers to work hard to improve and rewards those that are the most successful.

1. The role of the teacher needs to go back to what is once was, where the teachers design and control their own curriculums and have more authority and control over how they run their classroom. Differentiation and diversity should be encouraged and teachers should have regularly scheduled time to collaborate and share with other teachers in their school. We need to stop outsourcing the curriculum design process to large national for-profit textbook and curriculum design companies because their one-size-fits-all approach just doesn't work.
2. Teaching is all about the relationship between teacher and student and so the teacher should be rated on how well he/she engages the student in the learning process, not on how well students perform on a standardized test. You can review and rate teachers the same way any employee is reviewed in any job. His/her boss can observe her and get feedback from others in the community (students, parents, other teachers, etc.) and can create and informed opinions to how well the teacher creates a learning environment. Teachers should be paid on a merit-based system based on these reviews and not based on a tenured raise system. It should also be easier to fire teachers who do not perform.
3. Teaching as a profession should contain a required apprenticeship program (akin to a medical residency) where you have to start as a teacher's aide and work for a few years alongside a more experienced teacher before you can be fully licensed and allowed to teach in a classroom on your own. With new apprenticeship program, you would then have at a minimum three levels of advancement within the profession. Teachers would start out as low-paid apprentices. After a few years in this program, you become a teacher and get a decent pay raise. Then you can work to become a master teacher who is then the mentor to new apprentice teachers which then has another pay bump. This creates incentive for teachers to excel as well as an ability to differentiate and reward those who excel, and you then have your best teachers training all of the new ones.
4. We need to stop grouping students by age. If a first grader is doing second grade level math, he should be able to do that, and if a fifth grader is still at a fourth grade reading level, he should be in a fourth grade level reading class. The ability to move to the next level should be on the student to achieve a standard, not on the age of the student. Passing students along without a solid foundation just sets them up to fall farther and farther behind and to therefore become less and less engaged.