Addition and subtraction - Add and subtract two-digit and ​three-digit numbers not crossing 10 or 100​ - Planning

The Year 3 Autumn Addition and Subtraction curriculum is designed to enhance students' mental arithmetic and written calculation skills, specifically focusing on adding and subtracting two-digit and three-digit numbers without crossing the tens or hundreds. The objectives set by the National Curriculum include mental arithmetic involving three-digit numbers and ones, tens, and hundreds, as well as using formal written methods for columnar addition and subtraction. Students are also encouraged to estimate the answers to calculations and utilise inverse operations to verify their results. The key vocabulary introduced in this unit includes terms such as addition, subtraction, column addition, column subtraction, and estimate, which are fundamental to understanding and applying mathematical concepts effectively.

During the lessons, children are introduced to practical activities that solidify their understanding of place value and its role in addition and subtraction. They use resources like a place value chart, Base 10 blocks, and place value counters to visually represent and calculate sums and differences. For instance, a scenario involving planting carrot seeds is used to contextualise the addition of a three-digit number with a two-digit number, emphasising the importance of starting with the ones column and working across. Subtraction is similarly approached, with a focus on not needing to build both numbers. The lesson aims to correct common misconceptions such as misaligning place value columns and making both numbers when subtracting. Differentiated challenges are provided to cater to varying levels of proficiency, from working towards the expected level to achieving greater depth in understanding and applying these mathematical concepts.