Comment by candybar

The page you linked to doesn't have a single problem that requires "setting up equations with unknown variables and solving them." And as I mentioned, even in the US, "Algebra 1" isn't when Algebra in the sense of equations and variables is first introduced. Algebraic concepts are explicitly introduced around 5th grade (https://www.khanacademy.org/math/cc-fifth-grade-math/imp-alg...), but problems that could easily be considered algebraic (whether through word problems or explicit placeholders) may be introduced as early as 2nd/3rd grade.