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      Use equivalence and compensation strategies to solve problems

      You can use equivalence and compensation strategies to solve problems.

      Lesson 9 of 10
      New
      New
      • Year 6

      Use equivalence and compensation strategies to solve problems

      You can use equivalence and compensation strategies to solve problems.

      Lesson details

      Key learning points

      1. The part-whole structure can be used to represent additive problems.
      2. A bar model can be used to represent additive problems.
      3. A balance beam can be used to represent equivalence and compensation.

      Keywords

      • Equivalence - Equivalence is when two or more things have the same value.

      • Compensation - Compensation is a mental strategy which involves adjusting parts of an equation while maintaining equivalence.

      • Unknown - An unknown is a quantity that has a set value but it is represented by a symbol or letter.

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

      Common misconception

      Pupils might find it hard to understand that they needn't recalculate the parts after adjustment if the question wants the new whole.

      Show jottings and workings for two examples side-by-side. In the 1st example, calculate all the parts after adjustment as well as the new whole. In the 2nd, calculate only the new whole. Discuss with the pupils which is the most efficient and why.

      Pupils could create puzzles featuring three unknowns on each side themselves. All they'll need is six blank cards and some parameters, e.g. numbers between 1 and 5 featuring ones and tenths.
      Teacher tip

      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.
      What do expressions have if they are equivalent?

      Ticks next to them.
      Correct answer: The same value.
      More than one part.
      A whole.

      Q2.
      What is the unknown in the equation below? + 3 + 8 = 15

      Correct Answer: 4

      Q3.
      What is the unknown in the equation below? + 0.6 + 0.8 = 1.5

      Correct Answer: 0.1

      Q4.
      What is the unknown in the equation below? + 67 = 82 + 18

      Correct Answer: 33

      Q5.
      Which inequality symbol should go between these two expressions? 54 + 98 52 + 101

      Correct Answer: <

      Q6.
      Which inequality symbol should go between these two expressions? 3.6 + 2.3 3.3 + 2.1

      Correct Answer: >

      Assessment exit quiz

      6 Questions

      Q1.
      Which of the equations below is incorrect and does not contain two equivalent expressions?

      12 + 65 = 70 + 7
      11 + 66 = 69 + 8
      Correct answer: 10 + 66 = 68 + 9

      Q2.
      Calculate the unknown in this equation. 45 + = 97

      Correct Answer: 52

      Q3.
      Calculate the unknown in this equation. 1.3 + + 1.7 = 1.1 + 2.1 + 0.8

      Correct Answer: 1, 1.0

      Q4.
      Calculate the unknown in the empty box of this magic square.

      An image in a quiz
      Correct Answer: 8

      Q5.
      Calculate the unknown in the empty box of this magic square.

      An image in a quiz
      Correct Answer: 3.6

      Q6.
      Some of the inequality statements below are false. Can you spot them?

      34 + 0.145 + 109.25 > 100 + 9.25 + 34.135
      Correct answer: £67.50 + £67.70 + £67.90 < £67.70 + £67.70 + £67.70
      9,100,206 + 4,023,128 > 4,023,128 + 9,010,206
      Correct answer: 234.5 kg + 200 kg < 230 kg + 204 kg + 0.5 kg

      Lesson appears in

      UnitMaths / Use equivalence and compensation to simplify and solve addition calculations