I have mentioned this before, I am in 7th grade. My question is that in 5th grade, I learned about ecosystems in textbooks. So why are my teachers teaching it in 7th grade? Has there been any major changes to the education system since 2018?
Maybe you are supposed to be learning it in more depth now.
All learning spirals. You learn a little and then you continue on with revision and with adding a little more knowledge as time goes on.
Like climbing up a spiral staircase.
I have answered an earlier question for you.