School are union based for teachers. All get the same, whether you are the best instructor in the school or basically incompetent but managed to get lucky and land a job.
I have seen this myth repeated a lot about teachers, "they all make the same," along with its twin, "they can never be fired." Both of these are nothing more than right wing myths.
Teachers are paid according to two factors 1. years of experience and 2. level of education.
A school salary scale works like any other scale, the top line is a minimum salary for that district, that would vary by district, but lets us $30,000 as a beginning number. A first year teacher starts on that box 1 year, BA. The next line below it would be step 2, so they would get one step around $500 increase the second year. The lanes going across are based on education. BA, BA 15, BA 30, MA, MA 15, MA 30. Moving in this direction generally sees an increase in pay around $500 for each step.
Most districts allow you to bring in a set amount of years into the job, but they can give as many years as they want to give. Example, I was given 20 years experience on the scale when I moved to my current job 2 years ago. If you teach in an area of need, like Math, Science, Shop, Music, Band, Home Ec, they will start you further down on the scale. A 3rd grade position, I doubt it. Its supply and demand. Lots of elementary ed. majors few math and science majors.
The second part used to be true, but not now. When you get a teaching license you get a temp. for 2 years, after that time, if the district approves you are issued you full license. On the 3rd year contract was when you became tenured. That is no longer true, my district can fire me any time, Now there are rules that they have to follow but its not impossible.
Teaching is just like any other job, the skill level is bell shaped, I have taught with a few great teachers, a few horrible ones, and most are average. Poor teachers general do not last long in a district and are forced out. Not always, some slide through the cracks, but that happens everywhere. The poor teachers tend to be young educators, if it continues most leave the profession on the own or are forced out. Hell, one of the worst teachers I have ever seen was a decent BB coach, and now he is the Supt. in a growing district on the edge of Waukee.
Large schools pay more than small schools, and that is why its harder for smaller schools to keep good teachers, the difference between being at a 1A school to a 3A school is 10 to 15 K difference, doing the same job.