We understand the idea. In elementary school, students learn the elements. Originally, that meant learning to read, to write and to do arithmetic. "Originally" refers to schools for children about 6 years old in the early years of the US. Okay, for boys, not for girls, at least at first. (Being able to read and write are still not skills possessed by one in 7 or 8 people alive right now.) In most American elementary schools, children get some instruction in science, social studies, art, music and physical education.
In junior high (or middle school) and high school, studies are based on already being able to read and write, often read and listen to learn, but write to show learning. Studies in high school and college are often based on previous learning but revelations of controversy and doubt are also more likely to be found in studies for students of greater maturity. At more mature levels, students can handle learning that most theories and principles only apply part of the time, in given circumstances, and that complete agreement on anything is rare.
I am writing to emphasize that adults teaching on any level may be highly educated. Sometimes, knowing Miss Smith as your child's kindergarten teacher can bleed into thinking of Miss Smith as having a kindergarten mind. Miss Smith might have been a Wall Street financier or a prosecuting attorney. She might have retired or changed jobs. She might be the author of that bestselling novel about mind-blowing sex or the latest theological article critical of her church.
I wrote above that higher level studies can be based on previous levels and they sometimes are. However, one thing I have learned positively is that most ideas can be learned in what is often called "an intellectually honest form" by anybody interested in learning them. Teachers of younger children must be able to relate to them on a warm and supportive level but those same teachers don't necessarily stay only warm and supportive with adults.
The higher levels of education may include studies that involve danger, such as with chemicals or high-temperature welding or high-speed drills. Graduate schools tend toward knowledge creation and criticism as when a graduate student, already in possession of the bachelor's degree, engages in original research and explanation. Teachers of such students are usually highly educated but not in all fields. It is easy to forget that a high-level scientist may not know much about the history of a particular country or group while Miss Smith is an immigrant from there and a native speaker who gets back there every summer.