Mental Calculations Year 6 Four Operations Learning Video Clip

Step 14: Mental Calculations Year 6 Four Operations Learning Video Clip

Buzz is visiting Planet Zigzog to conduct some important research. Help him to overcome the problems he faces using mental calculations!

More resources for Autumn Block 2 Step 14.

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Discussion points for teachers

1.What temperature could be shown on the thermometer?
Discuss how we are unable to work out the answer with no intervals or end number on the scale. Discuss the possibilities for the end number and the possible temperatures that could be shown on the thermometer. This question is open-ended for the children to explore.
Various answers, for example: If the scale went up to 100°C then the temperature shown is approximately 40 °C

2.Help Buzz to use a mental strategy to work out the approximate average temperature on Zigzog over the last 5 days.
Discuss how the numbers can be rounded before adding mentally, then divided by 5 by dividing by 10 and doubling the answer.
If rounded to the nearest 10 before dividing by 5, the answer is 28°C.

3.Estimate how many people live here altogether.
Discuss what the words ‘population’ and ‘estimate’ mean. Discuss what we can do with the numbers to estimate the total. Discuss rounding up and down and when each is appropriate to use.
2,500

4.Can we use a mental calculation to find the exact answer?
Discuss if this is possible. Discuss the process we used to estimate the answer and how we can use this figure to help us find the exact answer.
Various answers, for example: Yes – we rounded 998 up 2 to 1,000, we rounded 1,002 down 2 to 1,000 and we rounded 499 up 1 to 500. We can subtract 1 from our estimate to find the exact answer of 2,499.

5.Estimate how many asteroids will be left in the field.
Discuss what we can do with the numbers to estimate the total. Discuss which order we should subtract the numbers to solve the problem most efficiently.
Various answers, for example: 2,140

6.What order would you choose to multiply these numbers to find the answer most efficiently?
Discuss if there is more than one possible answer to this question. Discuss the different ways we could work it out. Discuss which method we find most efficient and why. Discuss how our knowledge of times tables and multiplying by 10 helps us to solve the problem. This question is open-ended for the children to explore.
Various answers, for example: 30 x 3 x 6

7.Help Buzz work out the code.
Discuss the calculation using the method decided upon.
540

National Curriculum Objectives

Mathematics Year 6: (6C6) Perform mental calculations, including with mixed operations and large numbers

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