My son is learning algebra in 2nd grade. They don’t call it “algebra” yet nor mention “variables”, but they’re working on questions like solving “4 + ? = 9”.

He just goes to our local public elementary school.

Yeah I guess technically that's algebra but at that age it is based on memorization (you just learn that 4 + 5 = 9) and you're not actually using algebra to solve the problem e.g. "subtract 4 from both sides of the equation."

True, and it’s only 2nd grade, but it’s clearly setting the foundation for learning algebra properly.

Of course, when he asked for help with his practice problems I had no idea how they were meant to solve it so I taught him to solve it algebraically.