Anecdotal data from Estonia: I just checked what's the level of maths we have for the 3rd grade (which here corresponds to 9-10 year olds): (Google Translate):

Anecdotal data from Estonia: I just checked what's the level of maths we have for the 3rd grade (which here corresponds to 9-10 year olds): (Google Translate): * reads, writes, sorts and compares natural numbers 0–10,000; * presents a number as the sum of units, tens, hundreds and thousands; * reads and writes ordinal numbers; * adds and subtracts numbers mentally within 100, and in writing within 10,000; * knows the multiplication table (multiplies and divides by single-digit numbers mentally within 100); * knows the names of the members and results of four arithmetic operations; * finds the numerical value of a letter in equations by trial and error or by analogy; * determines the correct order of operations in an expression (parentheses, multiplication/division, addition/subtraction). So you have elements of pre-algebra but actual algebra will be covered only in the 4th/5th grade (10-12 yo).