I don't remember my school days, oddly. For my kids, they don't have an "algebra" class until later. But they do basic symbolic math far sooner. I know they have done what we would call linear systems of equations as early as 6th grade. Different number systems even earlier.

My 9th grader is in an algebra class. I don't remember if it is 1 or 2.

I'm still not entirely clear I see the obvious path from the things they are doing to algebraic types.