Halving, Doubling - Whole numbers, decimals

[josh2017]

hello,

have been teaching doubling , halving using partitioning (even, odd, odd at 100's, 1000's), halving decimals, what approach do you take to explain these topics for 11+ exams.

Any resources which explains the approach to take to explain this.

rgds,
josh

[Guest55]

Why would it be any different? Use a method the child understands and can perform quickly and accurately.

[josh2017]

Why would it be any different? Use a method the child understands and can perform quickly and accurately.

well i was explaining half 20.6 which she could break into money speak 20 pounds and 30 pence which gave 10.30

when she tried the same approach for halving 7.7 she got stuck, so what approach shall i try

i tried explaining partition 7.7 in 7 pounds and 70 pence half of which is 3 pounds 50 pence and 35 pence hence half of 7.7 is 3.85 {3 pounds 85 pence}
so my question is what approach do people here take to explain this topic

[Guest55]

How have they taught this at school? Does she use short division or ...

It's good to be flexible with the method you use - e.g. 1003 - 997 is much easier on a number line than a formal vertical [column] subtraction.

[josh2017]

How have they taught this at school? Does she use short division or ...

It's good to be flexible with the method you use - e.g. 1003 - 997 is much easier on a number line than a formal vertical [column] subtraction.

not taught at school yet, i had picked this as one of topics to teach for 11+ exam.
Are there any text books explaining these topics and approach to teach.

[Guest55]

Her school should have a calculation policy - alternatively I'd consult the national curriculum. Personally I feel it is a shame that some schools are tending to now focus too much on the 'traditional' methods rather than encouraging pupils to use the most efficient method.

https://www.gov.uk/government/publicati ... s-of-study" onclick="window.open(this.href);return false;

BTw, I'd spend more time on developing problem solving - look at http://www.nrich.maths.org" onclick="window.open(this.href);return false; for ideas linked to what she is learning at school.

[josh2017]

BTw, I'd spend more time on developing problem solving - look at http://www.nrich.maths.org" onclick="window.open(this.href);return false; for ideas linked to what she is learning at school.

thanks, any specific area you can point me to pls at nrich, with problem solving did you meant word problems or approach to solve a problem?

[Guest55]

I find the curriculum map https://nrich.maths.org/12662" onclick="window.open(this.href);return false; useful.

You can find problems linked to what she is learning. I think word problems and probelms solving are both important - and not just for 11+

Try this as well: https://nrich.maths.org/12757" onclick="window.open(this.href);return false;

What year is she is? I also lke the Primary Maths challenge - does her school do this? http://www.primarymathschallenge.org.uk/" onclick="window.open(this.href);return false;

There are some [free] old papers to download.

[josh2017]

I find the curriculum map https://nrich.maths.org/12662" onclick="window.open(this.href);return false; useful.

You can find problems linked to what she is learning. I think word problems and probelms solving are both important - and not just for 11+

Try this as well: https://nrich.maths.org/12757" onclick="window.open(this.href);return false;

What year is she is? I also lke the Primary Maths challenge - does her school do this? http://www.primarymathschallenge.org.uk/" onclick="window.open(this.href);return false;

There are some [free] old papers to download.

hi thank you, she is year 4 at the moment {sept born}

[RedPanda]

when she tried the same approach for halving 7.7 she got stuck, so what approach shall i try

A precursor to halving odd number decimals is a good understanding of place value. Does she understand that 0.7 is 7 tenths or 70 hundredths? Does she even understand what a tenth or hundredth is? You might need to take a step back before taking 2 forward.

Alternatively you could wait for the school to cover this topic (again?). Times tables and mental arithmetic in general are good topics to reinforce at home. Word problems are great too, just make sure they are age appropriate. Year 5 leaves plenty of time for filling the gaps which should have reduced after another year in school.