Solve subtraction calculations mentally by using known facts
Lesson details
Learning outcome
I can solve subtraction calculations mentally by using known facts
Key learning points
- Compensation can be used to simplify subtraction calculations.
- Equivalence can be used to simplify subtraction calculations.
- A number line can be used to represent compensation and equivalence.
Keywords
Minuend - The minuend is the number being subtracted from.
Subtrahend - A subtrahend is a number subtracted from another.
Partition - Partition is the act of splitting an object or value down into smaller parts.
Adjust - When you adjust you make a change to a number. This is done to make a calculation easier to solve mentally.
Common misconception
Known facts in this lesson include complements and two-digit subtractions which some children may find challenging to recall fluently.
It's a good idea, if possible, to do some pre-teaching here to develop the confidence of the children who might find the known facts aspect provides extra cognitive load. Supplying scaffolds such as key bonds to 20 and 100 may also benefit.
Teacher tip
For children who find it challenging to recall addition facts fluently, have a list of complements to 100 available to refer to. They might even find a hundred square useful.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.In the following equation, which number is the subtrahend?
21 − 4 =17
Q2.Solve the following calculation mentally by adjusting the minuend and subtrahend.
76 − 22 =
Q3.Solve the following calculation using a mental strategy.
= 150 − 68
Q4.Solve the following calculation mentally by adjusting the subtrahend and then the difference.
165 − 27 =
Q5.Solve the following calculation using a mental strategy.
= 4,050 − 98
Q6.Select the equivalent expressions (equal value) from the list below.
Assessment exit quiz
6 Questions
Q1.Use a known fact to find the missing number in this subtraction equation.
46 − 0.35 =
Q2.Use a mental strategy. = 223 − 0.57
Q3.Use a mental strategy.
27.43 − 0.22 =
Q4.Use a mental strategy.
= 274.86 − 0.54
Q5.Use a mental strategy.
1,367,000 − 17,000 =
Q6.Use a mental strategy. 9,284,000 − 22,000 =
To help you plan your 6 maths lesson on: Solve subtraction calculations mentally by using known facts, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 6 maths lesson on: Solve subtraction calculations mentally by using known facts, 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.