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      Explain how to balance equations with addition or subtraction expressions

      Lesson details

      Learning outcome

      I can explain how to balance equations with addition or subtraction expressions in different contexts.

      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

      • Peimeter - The perimeter is the distance around a 2D shape.

      • Expression - An expression contains one or more values, where each value is separated by an operator.

      • Area - Area is the measurement of a flat surface. It measures 2D space.

      Common misconception

      Pupils are inefficient when calculating the perimeter of a rectangle or do not recognise why more efficient strategies (summing length and width and doubling) works.

      Encourage pupils to see the efficient calculation and connection with smaller integers to support the generalisation before progressing to values in the lesson. Consider adapting values for some learners where required.

      Teacher tip

      In this lesson, equations with more than one operation are completed left to right, following the context. Brackets have not been used to show priority as pupils have not formally encountered this. Consider the learning journey of your own pupils and adapt if required.

      Licence

      This content is © Oak National Academy Limited (2025), 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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      Prior knowledge starter quiz

      6 Questions

      Q1.
      Which of the following expressions has the same sum as 41.6 + 7? Can you reason without calculating?

      Correct answer: 41 + 7.6
      41 + 7
      40.6 + 6
      Correct answer: 1.6 + 47

      Q2.
      What is the area of this rectangle? $$cm^2$$

      An image in a quiz
      Correct Answer: 80

      Q3.
      What is the area of this rectangle? Check the measurements carefully. $$cm^2$$

      An image in a quiz
      Correct Answer: 25.2

      Q4.
      What is the perimeter of this rectangle? cm

      An image in a quiz
      Correct Answer: 36

      Q5.
      Use an efficient strategy to calculate 132.7 + 489.92 =

      Correct Answer: 622.62

      Q6.
      Complete the equation that is represented by the bar model. 1,267 + c =

      An image in a quiz
      Correct Answer: 2,145 + 3,012 = 1,267 + c

      6 Questions

      Q1.
      True or false. Lawn A and lawn B have the same perimeter.

      An image in a quiz
      Correct answer: True
      False

      Q2.
      Which expressions can be used to represent the perimeter of this lawn?

      An image in a quiz
      Correct answer: 8.8 + 12.5 + 8.8 + 12.5
      8.8 × 2 + 12.5
      8.8 × 12.5 × 2
      8.8 × 12.5 + 2

      Q3.
      What is the missing dimension labelled x for this pair of lawns? m

      An image in a quiz
      Correct Answer: 38.6

      Q4.
      Lawn A and lawn B have the same area. What is the missing dimension labelled x on lawn B? m

      An image in a quiz
      Correct Answer: 4

      Q5.
      A is made up of lawn and pond. What is the area of the lawn? $$m^2$$

      An image in a quiz
      54

      Q6.
      The area of the whole garden is 99 $$m^2$$ and the area of the lawn is 78 $$m^2$$ What is the missing dimension of the pond labelled x? m

      An image in a quiz
      Correct Answer: 7

      To help you plan your 6 maths lesson on: Explain how to balance equations with addition or subtraction expressions, download all teaching resources for free and adapt to suit your pupils' needs...