This FREE Grade 3 Ontario mental math lesson teaches students how to use the break apart strategy to solve two-digit addition problems using place value understanding. Aligned to the Ontario 2020 Mathematics Curriculum (Strand B – B1.4), this ready-to-use lesson includes slides, student practice, and a classroom-friendly exit ticket. If you found this lesson helpful, the complete 15-lesson Grade 3 Ontario Strand B: Number Sense unit provides a fully structured plan for teaching the entire strand