New
New
Year 8

Securing understanding of rounding

I can recognise when values have been rounded and state sensible suggestions of what the unrounded value could have been.

New
New
Year 8

Securing understanding of rounding

I can recognise when values have been rounded and state sensible suggestions of what the unrounded value could have been.

Lesson details

Key learning points

  1. When a number has been rounded you can make conjectures about what the unrounded number could have been.
  2. Rounding can be very useful in real life contexts particularly measure.
  3. When working in some real life contexts you are often working to a certain degree of accuracy.
  4. Numbers in different contexts will be rounded to a different degree of accuracy (e.g. distance when walking or flying).

Common misconception

The assumption that if a number ends in 2 zeros it must have been rounded to the nearest hundred.

Choose examples that round to the same value when rounded to the nearest ten and hundred in this case. E.g. 398, rounds to 400 to the nearest ten and 400 to the nearest hundred.

Keywords

  • Conjecture - A (mathematical) statement that is thought to be true but has not been proved yet.

  • Degree of accuracy - A degree of accuracy shows how precise a number or measurement is. E.g to the nearest cm, nearest 10, 1 s.f., etc.

Get pupils to come up with their own 'what number am I?' problems. Emphasising that their clues must lead to a unique number. Pupils can then challenge each other to solve their problems or a pupil can present theirs to the whole class.
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).

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6 Questions

Q1.
Rounding means to change a number into another number that is approximately the same value, but is to work with.
Correct Answer: easier, simpler
Q2.
27 345 rounded to the nearest thousand is .
Correct Answer: 27 000, 27 thousand
Q3.
Lucas buys a t-shirt costing £22.25. What is the cost of the t-shirt to the nearest pound?
Correct Answer: £22.00, £22, 22
Q4.
Round 305.7298 to 1 decimal place.
Correct Answer: 305.7
Q5.
Round 0.06921 to 2 decimal places.
Correct Answer: 0.07
Q6.
Round 12.89528 to 2 decimal places.
Correct Answer: 12.90

6 Questions

Q1.
Degree of accuracy shows how a rounded number or measurement is.
Correct Answer: precise, exact
Q2.
Select the numbers that do not round to 14 000 when rounded to the nearest thousand.
Correct answer: 13 450
13 550
13 650
14 450
Correct answer: 14 550
Q3.
54 528 is 54 500 to the nearest ...
ten
Correct answer: hundred
thousand
ten thousand
hundred thousand
Q4.
Jacob estimates how many pieces of pasta are in a bowl of pasta. Which of the following is the most appropriate degree of accuracy in this situation?
Nearest integer
Correct answer: Nearest ten
Nearest hundred
Nearest thousand
Q5.
A charity is sending thank you cards to 160 people who have made donations. Stamps come in books of 12. How many books of stamps do they need to buy?
Correct Answer: 14, fourteen
Q6.
Izzy buys a large bag of 75 chocolate bars. She puts them into boxes of 4 to sell for charity. How many boxes will Izzy have to sell?
Correct Answer: 18, eighteen