Explain how adjusting the subtrahend affects the difference: reduction structure
Lesson details
Learning outcome
I can explain how adjusting the subtrahend affects the difference in a reduction 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.
Adjust - When you adjust you make a change to a number. This is done to make a calculation easier to solve mentally.
Common misconception
Pupils might think that if the subtrahend increases or decreases then so too does the difference. They might find it initially difficult to understand the idea of the inverse in the context.
Give lots of practical examples of this such as emptying out bottles or eating sweets demonstrating an increase in the subtrahend and its effect on the difference.
Teacher tip
You may wish to use the puzzles in Cycle 2 as a template for children to create their own puzzles. If you choose to do this, ensure you give them parameters so they create puzzles that are achievable without extravagant number choices.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Which value in this bar model is the minuend?
Q2.Solve the following calculation mentally by adjusting the minuend and subtrahend.
251− 36 =
Q3.Solve the following calculation mentally using unitisation.
= 620 − 350
Q4.Solve the following calculation mentally by adjusting the minuend and then the difference.
1,004 − 800 =
Q5.Solve the following calculation using a mental strategy.
= 202 − 47
Q6.Find the missing number in the equation below by adjusting the minuend.
= 749,000 − 21,000
Assessment exit quiz
6 Questions
Q1.Which word completes the following sentence?
The more we __________, the less we are left with.
Q2.Which word completes the following sentence?
The __________ the subtrahend, the smaller the difference.
Q3.Without calculating the value of each expression can you work out which symbol should go between these two expressions?
54 − 23 ___ 54 − 13
Q4.Without calculating the value of each expression can you work out which symbol should go between these two expressions?
987 − 156 987 − 256
Q5.Without calculating the value of each expression can you work out which symbol should go between these two expressions?
578,234 − 512,293 578,234 − 502,293
Q6.Without calculating the value of each expression can you work out which symbol should go between these two expressions?
9.2 − 1.3 9.2 − 1.03
To help you plan your 6 maths lesson on: Explain how adjusting the subtrahend affects the difference: reduction structure, 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: reduction structure, 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.