I was thoroughly confused when I found out how the US high school math curriculum is structured. To this day I can't remember what the hell is "precalculus". In my country I had separate textbooks on: functions; equations and inequalities; sequences and series; planimetry; stereometry; goniometry; analytical geometry; combinatorics, statistics and probability; complex numbers; mathematical analysis. Every time I refresh my knowledge on what "precalculus" is I promptly forget it again because it doesn't correspond to any of the fields that we were taught and that I'm used to think in terms of.