Have there been any major content (not pedagogy) changes in the basic US high school mathematics curriculum since the mid-1990's? More specifically, if I wanted to become a tutor of high school math today as someone who learned his secondary-level math skills back in the 1990's, would a review of my previous curriculum provide a decent foundation, or would there be skills or concepts that young people are learning that I would likely never have heard of?
As a background, I completed US high school mathematics (up through basic Calculus) in the 1990's. Back then, there was a heavy focus on hand-drawing graphs, along with some level of acceptance of black-and-white 8-bit Z80 graphing calculators as an aid to comprehension. I later completed university level coursework (at least through Linear Algebra) in the early 2000's. My understanding is that students nowadays are drawing fewer hand-graphs and using more and more technical modeling technology, but does this primarily represent changes in pedagogy, or are there concepts that high schoolers are learning today that would not have been covered in the 1990's?
I'm not asking about becoming a full classroom teacher (which would obviously require a strong foundation in modern pedagogy). I'm looking for something along the lines of "Oh, nearly every Algebra II class nowadays covers Smooran's Theorem of Transdynamic Coordination, but it was first discovered in 2008 so you probably never studied it.", or something slightly weaker. I'm not asking about general pedagogical changes like online discussion boards or video chat that we really didn't have access to.