Here is a list of all of the math skills students learn in grade 4! These skills are organized into categories :

Number sense,
Addition,
Subtraction,
Multiplication,
Division,
Variable expressions,
Functions,
Logical reasoning,
Patterns and sequences,
Money,
Units of measurement,
Time,
Understand fractions,
Decimals

Source : 
https://ca.ixl.com/math/grade-4