New
New
Year 7

Checking and securing understanding of written addition and subtraction strategies

I can generalise and fluently use written addition and subtraction strategies, including columnar formats, with decimals.

New
New
Year 7

Checking and securing understanding of written addition and subtraction strategies

I can generalise and fluently use written addition and subtraction strategies, including columnar formats, with decimals.

Lesson details

Key learning points

  1. Addition and subtraction strategies can make calculations easier.
  2. The decimal point can help ensure that digits with the same place value are combined.
  3. The decimal point will not help if the values are not measured in the same units.

Common misconception

When subtracting you always write the bigger number above the smaller number.

The context of spending money should help with this, as they will end up with a positive balance which is not possible .

Keywords

  • Metric - Metric units are based around the standard units of metre, gram and litre.

  • Additive inverse - The additive inverse of a number is a number that, when added to the original number, gives the sum of 0.

  • Absolute value - The absolute value of a number is its distance from zero. E.g. 5 and (-5) are both 5 away from zero and so both have an absolute value of 5.

This lesson lends itself to having important discussions about sensible finances as it talks about negative bank balances.
Teacher tip

Equipment

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.
Complete the statement. The additive of a number is a number that, when added to the original number, gives the sum of zero.
Correct Answer: inverse
Q2.
Match together each of these subtractions with its equivalent addition.
Correct Answer:8 - 5,8 + (-5)

8 + (-5)

Correct Answer:5 - 8,5 + (-8)

5 + (-8)

Correct Answer:8 - (-5),8 + 5

8 + 5

Correct Answer:(-5) - 8,(-5) + (-8)

(-5) + (-8)

Q3.
Match each calculation to its answer.
Correct Answer:8 - 5,3

3

Correct Answer:5 - 8,(-3)

(-3)

Correct Answer:8 - (-5),13

13

Correct Answer:(-5) - 8,(-13)

(-13)

Q4.
Work out 12 - (-8)
-20
-4
4
Correct answer: 20
Q5.
Select the calculations which are equivalent to 15 - 20
Correct answer: 15 - 15 - 5
Correct answer: 15 + (-15) + (-5)
15 - (-15) - (-5)
Correct answer: 15 + (-20)
15 + (-15) - (-5)
Q6.
Lucas has a balance of £2.72 at the school canteen. He spends £5. What is Lucas' new balance?
-£7.72
Correct answer: -£2.28
-£2.38
£2.28
£2.38

6 Questions

Q1.
Select the best word to complete the statement. __________ units are based around the standard units of metre, gram and litre.
Basic
Decimal
Imperial
Measuring
Correct answer: Metric
Q2.
Mr Oak's bank account has a balance of £125. He spends £160. What is Mr Oak's new balance?
£285
£35
£25
-£25
Correct answer: -£35
Q3.
The balance on a bank account is £1475. What is the new balance after a holiday costing £1750 has been paid for?
-£225
Correct answer: -£275
-£325
-£375
Q4.
Jun has sunflower that is 2.36 m tall. Aisha has a sunflower that is 148 cm tall. What is the total height of their sunflowers in metres? metres
Correct Answer: 3.84, 3.84m, 3.84 m, 3.84 metres
Q5.
Which of these show a correct calculation to find the total of 3.2 km, 2460 m and 342 cm ?
3.2 + 2.46 + 0.342
3200 + 2460 + 34.2
Correct answer: 3200 + 2460 + 3.42
Correct answer: 320 000 + 246 000 + 342
3.2 + 2.46 + 3.42
Q6.
Complete the statement. The missing value in this addition pyramid is cm.
An image in a quiz
Correct Answer: 391, 391 cm, 391cm