We didn't learn imaginary numbers until Algebra 1. Not a lot of us took that in Jr hi. Well, I did, but the excellent teacher we had went to teach at the high school, so we got the world's worst Algebra teacher. I'd ask her a question and be more confused afterward, so I learned to figure things out on my own. I felt bad for the kids who couldn't do that and got no help from our very nice but clueless teacher.