Explain how to balance equations with subtraction expressions
Lesson details
Learning outcome
I can explain how to balance equations with subtraction expressions.
Key learning points
- If the minuend and subtrahend are changed by the same amount, the difference stays the same.
- If you increase or decrease the minuend, the difference increases or decreases by the same amount.
- If you increase the subtrahend then the difference decreases.
- If you decrease the subtrahend then the difference increases.
Keywords
Unknown - An unknown is a quantity that has a set value but it is represented by a symbol or letter.
Equation - An equation is used to show that one number, calculation or expression is equal to another.
Expression - An expression contains one or more values, where each value is separated by an operator.
Common misconception
Pupils immediately calculate expressions instead of considering the relationship between expressions.
Take time to model interrogation of values within expressions, identifying relationships between them. Encourage this reasoning and show how it can be more efficient than calculation especially in situations with larger values.
Teacher tip
Letters are used to represent an unknown in this lesson, which pupils may be less familiar with. Take time to show pupils that any letter can be used to represent an unknown value. Letters from the start or end of the alphabet are more commonly used.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Which of the following expressions has the same sum as 306 + 30? Can you reason without calculating?
Q2.Round 23,654 to the nearest multiple of 10
Q3.Use an efficient strategy to calculate 56.75 + 22.25 =
Q4.Use the correct inequality symbol to make this correct: 349,207 349,086
Q5.Use rounding, estimating, comparing or reasoning to determine the missing symbol in this inequality statement. 36 + 23 23 + 47
Q6.Use an efficient strategy to calculate 10,000 − 8,655 =
Assessment exit quiz
6 Questions
Q1.Select the correct symbol to compare the expressions. 40.36 − 21.63 ___ 39.86 − 27.91
Q2.Select the correct symbol to compare the expressions. 12,453 − 6,104 ___ 27,896 − 19,317
Q3.The unknown subtrahend in the diagram below is
Q4.Use an efficient strategy to calculate the unknown value g in g − 26,100 = 47,865 − 28,300
Q5.Use an efficient strategy to calculate the unknown value g in 46.5 − 12.6 = 107.9 − g
Q6.Izzy begins with 350 g of plasticine and removes 125 g. Jun begins with an unknown mass of plasticine and removes 90 g. Now they have the same mass of plasticine. How much did Jun begin with? g
To help you plan your 6 maths lesson on: Explain how to balance equations with subtraction expressions, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 6 maths lesson on: Explain how to balance equations with subtraction expressions, 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 Calculating using knowledge of equivalence in addition and subtraction unit, dive into the full primary maths curriculum, or learn more about lesson planning.