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

Mental Addition Strategies: Partition, Count on and Near Doubles

Learn three mental addition strategies—partition, count on, and near doubles—and choose the best one to match the numbers you're adding. Use number lines to show your jumps.

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    1 - Getting Started ~4 mins

    Illustration for Getting StartedHere is a quick one to do in your head: what is 38 + 27?

    Think it through quietly first, then we will share answers aloud. When you have an answer, notice the very first thing you did in your head to work it out.

    Tip

    There is more than one good way to add these numbers, so every method is welcome. We want to hear them all.

    👇 Mark your steps as done as you complete them.

    +5 XP

    2 - Watch and Notice ~9 mins

    The number line shows three additions, each solved a different way. Watch how the jumps land and see if you can name the strategy each time.

    👇 Mark your steps as done as you complete them.

    +10 XP

    3 - Try It Together ~11 mins

    Today we work through these additions together on the number line: 48 + 23, then 27 + 29, then 55 + 8. One pupil works at the board while the rest of us follow along and confirm the landing number.

    Key point

    For each one, we draw the jump arcs to reach the total, and we say which strategy we chose before we start. Sometimes we bridge to a friendly ten — that means we hop to the nearest tidy ten first, like 50 or 60, before adding the rest.

    Add it on the line

    +15 XP

    4 - Work It in Your Copy ~3 mins

    COPYBOOK MOMENT

    In your maths copy, work out these three additions. Each time, write the strategy name you chose beside the answer.

    • 47 + 25
    • 39 + 39
    • 58 + 6

    The strategy names you can choose from are partition, count on and near double.

    +10 XP

    5 - Class Challenge ~8 mins

    Today we take on a set of additions that step up in difficulty: 26 + 17, then 48 + 35, then 67 + 28, then 89 + 46. Add the jumps along the line to reach each total, and choose the strategy that fits the numbers.

    Tip

    The last sum, 89 + 46, is a stretch: it crosses past 100 into the hundreds, so its jumps are bigger. If that one feels tricky, just watching the jumps and predicting the landing number is plenty.

    Reach the total

    +15 XP

    6 - What Did We Notice? ~2 mins

    MATHS TALK

    When is partition faster than counting on, and when is the opposite true? Think of a sum where each one would be your first choice.

    +10 XP

    7 - What's Next ~3 mins

    What we learned

    • Good adders choose a strategy to fit the numbers rather than reaching for one method every time.
    • Partition splits a number into tens and units; counting on hops to a friendly ten first; a near double uses an almost-twin and adjusts by the small difference.
    • Every strategy can be drawn as jump arcs on a number line.
    Coming up

    Next we look at mental subtraction strategies, including counting up to find the difference between two numbers.

    +5 XP
    Pupil practice
    Module 2 · The Four Operations: Mental and Written Number
    Lesson 14 · Mental Addition Strategies: Partition, Count on and Near Doubles
    Download Activity Book page (PDF)
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