@Astronuc, your experience in school is not uncommon. I had a friend who completed all of high school math by eighth grade. The school had no intermediate programs like today's IB or AP courses, so they had to fund him to attend a local college so that by 12th grade, he had completed four years of undergraduate math.
In my case, I was nowhere near his accomplishments. I do recall the grade school structured classroom. In first grade, you get grouped into one of three reading classes and remain in that group as you meander through grade school. The teacher would schedule the reading groups: advanced, medium, and slow. Other courses like math, science and geography were structured around the three reading groups.
As one group read, the others did math or science. The other subjects were arranged in the same way, so that my group, group three, was always the last to learn. One time, I saw the kids doing long division, which looked really interesting, and I wanted to learn it, but I was told I had to wait until we got to that lesson.
To this day, I've never forgotten about that rebuke and how sad I felt about it. Once you were assigned a reading group, there was no means of advancing beyond the other students. We were the rearguard of learning, and we always felt left behind.
When sixth grade came around, my teacher encouraged me in science. My first report was on atomic energy ie basically structuring my project after an article in the Parade magazine, a popular Sunday paper insert. It featured striking images of a future powered by atomic energy.
In the closing days of sixth grade, my teacher met with each student and their parents. In my case, he told my mom I was college material, reading at an 8th-grade level. He gave me the remaining books we had to read for the elementary school curriculum and said, "Take these home and come back and tell me you read them." Huh?
He placed me on equal footing with the fast readers for middle school, breaking the spell of the slow-reading group. I am forever grateful for his encouragement. It changed my outlook on learning.
Basically, school is about grouping kids into smaller groups so that the teacher can juggle teaching all the required material for that grade. However, for slow readers, we might learn it in the next higher grade because we were the last to learn it.
Also, I think it had to do with resource management, where each class had a limited set of reading books, say about 12 for each book we needed to read. The fast group would get first crack, finishing in two weeks; then the middle group would get those books and maybe take a month; and finally the slow group would get those books, 2 months later, while behind the other students in all subjects.
This was in the late 1950s and early 1960s. As an aside, my mom wanted to improve my reading, so she had me read The Bobbsey Twins, a book series she had read in grade school.
In response, I started getting Scholastic Book Club books on Rocks and Minerals, Codes and Ciphers, Strangely Enough, and others to escape the curse of the Bobbsey Twins.
I had wanted to read Tom Swift, but our library didn't have them, or I didn't know where they were. The next best thing was the
Childhood of Famous Americans series: Albert Einstein, Abraham Lincoln, Thomas Edison, and other interesting people.
and so it goes...