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Maths Question Help

Posted: Tue Oct 26, 2021 1:56 pm
by 2021EnTrY
Please can someone help me with the explanation to this basic maths question?

-1 - -5


To me, its should be -6 but the answer in the CGP book is 4

if the question is like that
-1 -(-5) the answer is 4

Please can someone explain me an easier way to explain it to my DS

Re: Maths Question Help

Posted: Tue Oct 26, 2021 2:26 pm
by KaB£H1s3
2 negatives make a positive

Re: Maths Question Help

Posted: Tue Oct 26, 2021 4:35 pm
by 2021EnTrY
Thanks for your reply.

Any idea how to explain this to a kid.?

I tried using the number line method but still was unable to figure out how to explain this.

Any resource/suggestion will be extremely appreciated.

Re: Maths Question Help

Posted: Tue Oct 26, 2021 4:48 pm
by yoyo123
2021EnTrY wrote:Thanks for your reply.

Any idea how to explain this to a kid.?

I tried using the number line method but still was unable to figure out how to explain this.

Any resource/suggestion will be extremely appreciated.
Start at 0 step back 1 to -1. Then “take away” 5 steps, go 5 steps in opposite direction. Where do you end up?

Try it with lots of different numbers.
I find it works to use a counter or similar and get child to physically move it along (or up and down) the number line.

Re: Maths Question Help

Posted: Tue Oct 26, 2021 6:04 pm
by solimum
The "balloons and sandbags" model can hehlp: positive numbers are like balloons (or puffs of helium) which give "lift", negative numbers are like sandbags which pull you down. Hence removing sandbags ("taking away a negative number") has the same effect as adding more balloons

Just rote learning "two negatives make a positive" is potentially unhelpful without grasping the concepts at an instinctive level

I could only find some American videos describing this :

first addition
https://www.youtube.com/watch?v=2KWGsEU4kDE" onclick="window.open(this.href);return false;
then subtraction
https://www.youtube.com/watch?v=8wQkVr6GE-M" onclick="window.open(this.href);return false;

There's also an nrich game using the same concept https://nrich.maths.org/9941" onclick="window.open(this.href);return false; and you can download templates to make copies - perfect half-term fun... https://www.tes.com/teaching-resource/a ... e-11679644" onclick="window.open(this.href);return false;