New
New
Year 6

Explain how to balance equations with addition or subtraction expressions

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

New
New
Year 6

Explain how to balance equations with addition or subtraction expressions

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

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.

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.

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.

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).

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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? $$cm^2$$
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Correct Answer: 80
Q3.
What is the area of this rectangle? Check the measurements carefully. $$cm^2$$
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Correct Answer: 25.2
Q4.
What is the perimeter of this rectangle? cm
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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 =
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Correct Answer: 2,145 + 3,012 = 1,267 + c

6 Questions

Q1.
True or false. Lawn A and lawn B have the same perimeter.
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Correct answer: True
False
Q2.
Which expressions can be used to represent the perimeter of this lawn?
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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
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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
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Correct Answer: 4
Q5.
A is made up of lawn and pond. What is the area of the lawn? $$m^2$$
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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
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Correct Answer: 7