Estimate and Approximate Year 5 Addition and Subtraction Learning Video Clip

Step 3: Estimate and Approximate Year 5 Addition and Subtraction Learning Video Clip

Tripp and Tori visit Australia. There, they use estimation on a number line and in calculations.

More resources for Autumn Block 2 Step 3.

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Discussion points for teachers

1. What can Tripp and Tori do to work out approximately how far they have travelled?
Discuss options instead of guessing – estimate, approximate round etc.
They know that one quarter of the distance is 2,535km is approximately half way so they can estimate how far the full distance is.

2. What would be a suitable estimation of the distance Tripp and Tori have travelled?
Discuss how far Tripp and Tori have already travelled and how this can inform their answer. Discuss that the answer does not need to be exact. Discuss what would be best to round to and why.
2,500 x 4 = 10,000km

3. Approximately how many people visited the Opera House over the last three days?
Discuss method of rounding to suitable 1,000 to estimate the answer.
16,000 + 22,000 + 6,000 = 44,000

4. Why are our answers different?
Discuss why answers might be different - rounding to different numbers: nearest 10, 100 and 1,000. Why might we round to one of these instead of another? Discuss speed and accuracy.
The answers are different because Tripp rounds to the nearest 100 and Tori rounds to the nearest 1,000.

5. How many answers can you give and how accurate are they?
Discuss rounding to 10, 100 and 1,000. Discuss which is the most accurate and why. This question is open-ended for the children to explore.
Various answers, for example: 79,000 animals. This would be the least accurate as it is rounded to the nearest 1,000.

6. Estimate if there is enough grass to feed all the animals.
Discuss necessary information – the snakes do not eat grass so should not be included. Discuss rounding to nearest whole and then subtracting.
There is enough grass to feed the animals (32 + 13 + 15 = 60kg).

Optional Discussion Points:
How long might it take to drive from Sydney to Uluru, 2,840km away? If Uluru is quite central, approximately how many kilometres is Australia from east to west? Why might this not be the most accurate estimation?

National Curriculum Objectives

Mathematics Year 5: (5C3) Use rounding to check answers to calculations and determine, in the context of a problem, levels of accuracy

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