L6 Use Factors to Simplify Calculations

This Year 4 Maths lesson focuses on using factor pairs to simplify multiplication, building on prior learning in multiplication, division, and mental strategies from Year 4 and Year 3 summer term. The lesson begins with a reasoning problem where students explore misconceptions about factors, helping them understand that larger numbers or even numbers do not always have more factors. This sets the stage for exploring how factor pairs can make calculations easier. The introduction demonstrates how factor pairs can simplify multiplication. Using examples such as 24 × 6 or 30 × 12, students see how breaking numbers into factor pairs allows mental calculations to be completed efficiently. Techniques such as regrouping numbers, applying commutativity, and creating “friendly” numbers like 100 are highlighted to show how complex calculations can be made more manageable. In the main activity, children work in small groups on prepared multiplication tasks. Each group simplifies the calculations using factor pairs, records their answers, and writes an explanation of their chosen strategy. This encourages collaboration, reasoning, and clear communication of mathematical thinking. The plenary consolidates learning through an interactive “easy or hard” game, where students decide whether calculations can be simplified using factor pairs. This helps reinforce the lesson’s key concepts, emphasizing that larger numbers are not always harder and that strategic factor selection can make mental multiplication quicker and more accurate. Common misconceptions are addressed throughout, including confusing factors with multiples, overcomplicating calculations by breaking numbers into too many factors, and underestimating the power of commutativity or regrouping. This lesson is ideal for primary educators looking to strengthen Year 4 students’ mental multiplication strategies, promote mathematical reasoning, and improve confidence in handling larger numbers efficiently.