Mathematics
Intermediate
40 mins
Teacher/Student led
Learning Goals
Learning Outcomes
Lesson Files
+80 XP
What you need:
IWB/Projector/Large Screen

Mental Addition Strategies: Partitioning and Compensating

Learn three mental addition strategies—partitioning, compensating, and bridging—and choose which one fits the numbers you're adding. Use number-line jump arcs to show your thinking.

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    1 - Getting Started ~4 mins

    Illustration for Getting StartedHere is a sum: 47 + 38. No paper, no columns. How could you work this out in your head? There is more than one way, and some ways are quicker than others depending on the numbers.

    👇 Mark your steps as done as you complete them.

    +5 XP

    2 - Watch and Notice ~9 mins

    We will take the same sum, 47 + 38, three different ways, then a bigger sum at the end. Notice where each set of jumps lands and see what stays the same.

    👇 Mark your steps as done as you complete them.

    +10 XP

    3 - Try It Together ~11 mins

    Today we explore one sum together: 56 + 27. First we choose a strategy, then we draw the jump arcs to land on the answer.

    Choose a strategy and jump

    +15 XP

    4 - Work It Three Ways in Your Copy ~3 mins

    COPYBOOK MOMENT

    In your maths copy, take the sum 47 + 38 and work it three ways, one under the other: once by partitioning, once by compensating, once by bridging to fifty. Write the jumps you used beside each one. Then decide which way you would choose if you had to do it quickly.

    +10 XP

    5 - Class Challenge ~8 mins

    Today we work through these sums and reach each target in the fewest jumps you can: 47 + 38, then 56 + 27, then 235 + 198, then 268 + 197. The numbers get bigger, so think about which strategy keeps your jumps to a minimum each time.

    Reach the target in the fewest jumps

    +15 XP

    6 - What Did We Notice? ~3 mins

    MATHS TALK

    One pupil says partitioning is always best. Another says compensating is best for 235 + 198. Who is right, and how would you settle it? Which strategy fits 47 + 38, and which fits 235 + 198?

    +10 XP

    7 - What's Next ~2 mins

    What we did today

    • We added two-digit and three-digit numbers in our heads using jump arcs
    • We learned three strategies: partition, compensate, and bridge to a friendly ten
    • We saw that the numbers decide which strategy is quickest
    Coming up

    Next we move from mental jumps to the written column method, where we line up the units and add column by column with regrouping.

    +5 XP
    Pupil practice
    Module 2 · Operations and Computational Fluency Number
    Lesson 18 · Mental Addition Strategies: Partitioning and Compensating
    Download Activity Book page (PDF)
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