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mental maths and numberlines

Posted: Fri Oct 28, 2011 2:34 pm
by fatbananas
Hello,

Can someone tell me if, when adding, say, 56+38, it is best to learn to do lots of this sort of question with number lines first, so that you can mentally picture the numberline at some point and do these sums mentally? My year 3 DS seems to be imagining the numberline in this way: 56 + 30 and getting to 86 quickly but then has to practically count on his fingers to add the remaining units, instead of being able to mentally bridge the 10 on a numberline and so on.

Hope that made sense :oops: . I just wondered if doing lots of these sums with a numberline would help him to finally get it mentally, or whether there was a more efficient method.

Thank you!

Re: mental maths and numberlines

Posted: Fri Oct 28, 2011 2:37 pm
by Guest55
Yes - number lines are a good support -

I'd encourage him to tackle 56 + 38 by one of

* 56 + 30 = 86 then + 4 to get 90 then add the remaining 4 (this avoids bridging the ten)

* adding on 40 and subtracting 2 - it's quicker!

Re: mental maths and numberlines

Posted: Fri Oct 28, 2011 3:03 pm
by fatbananas
Thanks so much Guest55. I thought adding units to the nearest 10, in this case 90 and then adding on til you've added all the remaining units, was called 'bridging through 10'! :oops:

and, yes, I can see that adding 40 and subtracting 2 is far better - much quicker. Thank you!

Re: mental maths and numberlines

Posted: Fri Oct 28, 2011 3:12 pm
by Guest55
You can call it bridging through 10 ... :D

http://ictgames.com/bridgingThro.htm" onclick="window.open(this.href);return false; has some games about it ...

Re: mental maths and numberlines

Posted: Fri Oct 28, 2011 3:39 pm
by fatbananas
They look great games. Thank you very much!

Re: mental maths and numberlines

Posted: Fri Oct 28, 2011 5:00 pm
by yoyo123
Guest55 wrote:You can call it bridging through 10 ... :D

http://ictgames.com/bridgingThro.htm" onclick="window.open(this.href);return false; has some games about it ...
I've used the catapult one with y5/y6 children who found it hard to visualise and it was very useful

Re: mental maths and numberlines

Posted: Fri Oct 28, 2011 5:26 pm
by fatbananas
Thanks for the pointer, Yoyo :D