Explain how adjusting the subtrahend affects the difference: partitioning
Lesson details
Learning outcome
I can explain how increasing or decreasing the subtrahend affects the difference in a partitioning structure.
Key learning points
- The more you subtract the less you are left with.
- The less you subtract the more you are left with.
- A number line can be used to represent the change in the subtrahend.
Keywords
Minuend - The minuend is the number being subtracted from.
Subtrahend - A subtrahend is a number subtracted from another.
Difference - The difference is the result after subtracting one number from another.
Common misconception
The proportionality of bar models is something that children sometimes find tricky and causes them concern.
Remind them that accuracy is not completely necessary so long as they have roughly sized the parts (subtrahend and difference in these contexts). Alternatively, give them number rods to arrange as bar models and then draw around.
Teacher tip
Collect some example of money use that match the concept from the children. Have you ever saved for something but spent some of your savings on something else instead?
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.If the difference is 19, which part of the bar model below is the subtrahend?
Q2.Solve the following calculation mentally by adjusting the minuend and subtrahend.
456 − 42 =
Q3.Solve the following calculation mentally using unitisation.
= 890 − 540
Q4.Solve the following calculation mentally by adjusting the minuend and then the difference.
3,005 − 1,200 =
Q5.Solve the following calculation using a mental strategy.
= 903 − 46
Q6.Without calculating the value of each expression can you work out which symbol should go between these two expressions?
8.04 − 2.3 8.04 − 3.2
Assessment exit quiz
6 Questions
Q1.Look at the image of the counters. What is being referred to by the question mark?
Q2.True or false? If the minuend stays the same and the subtrahend decreases then the minuend and subtrahend will be further apart on a number line.
Q3.Look at the jottings. Which word would you use to complete the following sentence?
I’ve kept the minuend the same and subtracted 15 from the subtrahend so I had to 15 to the difference
Q4.Look at the jottings. Which same number works in both gaps in this sentence?
I’ve kept the minuend the same and added to the subtrahend so I had to subtract ___ from the difference.
Q5.Look at the jottings. What was the value of the adjustment to the subtrahend and the difference?
Q6.Which number in the final equation shown is incorrect?
To help you plan your 6 maths lesson on: Explain how adjusting the subtrahend affects the difference: partitioning, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 6 maths lesson on: Explain how adjusting the subtrahend affects the difference: partitioning, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 2 maths lessons from the Use equivalence and compensation to simplify and solve subtraction problems unit, dive into the full primary maths curriculum, or learn more about lesson planning.