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Year 6

Explain how to balance equations with addition and subtraction expressions

You can explain how to balance equations with addition and subtraction expressions

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New
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Year 6

Explain how to balance equations with addition and subtraction expressions

You can explain how to balance equations with addition and subtraction expressions

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Lesson details

Key learning points

  1. If one addend is increased and the other is decreased by the same amount, the sum stays the same.
  2. If the minuend and subtrahend are changed by the same amount, the difference stays the same.

Keywords

  • Equation - An equation is used to show that one number, calculation or express is equal to another.

  • Expression - An expression contains one or more terms or numbers, where each term or number is separated by and operator but an expression does not have an equals sign.

Common misconception

Thinking that you can change the values of subtraction and addition expressions by making the same changes.

Go back and explore what happens when you change different elements of addition and subtraction equations. Use stem sentences from earlier learning to highlight what happens to the sum and difference when values are changed in equations.

This lesson moves on to thinking about larger numbers within the equations. The numbers have been chosen so that children can still use mental strategies and can apply their understanding of place value and unitising to think about 28 thousands rather than calculating with 5-digit numbers.
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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Starter quiz

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6 Questions

Q1.
Round 8,907 to the nearest multiple of 10
Correct Answer: 8,910
Q2.
Which of the following expressions has the same difference as 150 − 30? Can you reason without calculating?
Correct answer: 170 − 50
Correct answer: 130 − 10
160 − 20
150 − 40
Q3.
Use an efficient strategy to calculate 27,648 + 32,963 =
Correct Answer: 60,611
Q4.
Use an efficient strategy to calculate 10 − 7.452 =
Correct Answer: 2.548
Q5.
What is 8.96 when rounded to the nearest whole number?
Correct Answer: 9
Q6.
Use an efficient strategy to calculate the unknown value g in g − 1,508 = 4,650 − 1,600
Correct Answer: 4,558

Exit quiz

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6 Questions

Q1.
Match each addition expression to an equal subtraction expression.
Correct Answer:140 + 120, 390 − 130

390 − 130

Correct Answer:150 + 120,400 − 130

400 − 130

Correct Answer:160 + 120,410 − 130

410 − 130

Correct Answer:170 + 120,420 − 130

420 − 130

Q2.
Which of these equations are balanced?
Correct answer: 32,000 + 5,000 = 58,000 − 21,000
32,000 + 6,000 = 58,000 − 21,000
33,000 + 7,000 = 59,000 − 21,000
Correct answer: 33,000 + 6,000 = 59,000 − 20,000
Correct answer: 33,000 + 5,000 = 59,000 − 18,000
Q3.
What is the missing addend needed to balance this equation? 48,000 + = 71,000 − 15,000
Correct Answer: 12,000
Q4.
What is the missing subtrahend to balance this equation? 52,000 + 9,000 = 79,000 −
Correct Answer: 18,000
Q5.
This equation is unbalanced. 65,000 − 8,000 = 18,000 + 38,000 How can you change 18,000 in the addition expression to balance the equation?
Correct answer: Increase 18,000 by 1,000
Decrease 18,000 by 1,000
Increase 18,000 by 10,000
Decrease 18,000 by 10,000
Q6.
This equation is unbalanced. 55,500 − 8,000 = 22,250 + 26,250 What should the subtrahend be to balance this equation?
Correct Answer: 7,000