"Demonstrate an understanding of addition (limited to 1 and 2-digit numerals) with answers to 100 and the corresponding subtraction by: using personal strategies for adding and subtracting with and without the support of manipulatives; creating and solving problems that involve addition and subtraction; explaining that the order in which numbers are added does not affect the sum; explaining that the order in which numbers are subtracted may affect the difference."
New Brunswick Grade 2 Math Curriculum
Two digit addition and subtraction is first taught in grade 2. Parents are often unaware of the strategies that students are being taught and do not understand why the traditional algorithms they were taught for solving addition and subtraction is not used.
Traditional algorithms are taught later in elementary school, but at the early stages it is important for students gain a strong number sense and understanding of place value.
PSSC Math Presentation.pdf