I don’t know what will happen in the future of course, but my son was doing simultaneous linear equations in third grade, and not really having problems with it

I don’t know what will happen in the future of course, but my son was doing simultaneous linear equations in third grade, and not really having problems with it tbh. He’s started 4th grade now, and is doing exponentials with constant powers, next up is exponentials with variable powers, and then the quadratic formula, though they introduce it gradually. He ought to be doing that pretty much for the final third of the year.