Year 4 struggling with decimals

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workingmom
Posts: 112
Joined: Thu Dec 11, 2014 10:47 am

Year 4 struggling with decimals

Post by workingmom »

Hi all you helpful people out there

Yesterday night (again after a long day at school and swimming) my DD and I had a bit of a struggle with decimals.

She is currently in Year 4 and have just started with Decimals. I am helping her out in understanding the ordering and how multiplying and dividing them with 10, 100 and 1000.
Things became tricky when some of the questions we encountered had a a decimal number conversion from kg to g and then m to km.
Both concepts when discussed separately, she knew i.e the multiplication/division of decimals and conversion, but when both of these came together, she didnt quite get them.

Wonder if other mums are seeing the same of their kids in year4 and how are they helping them ?
Guest55
Posts: 16254
Joined: Mon Feb 12, 2007 2:21 pm

Re: Year 4 struggling with decimals

Post by Guest55 »

This is another step as they need to know e.g. 1000m = 1km and understand that there will be more metres than kilometres for the same distance. It is a bit more challenging than just multiplying and dividing.

May I ask if the school has made it clear that decimal points don't move?
workingmom
Posts: 112
Joined: Thu Dec 11, 2014 10:47 am

Re: Year 4 struggling with decimals

Post by workingmom »

Honestly, I am not sure how they have explained it.
But I did see that her last week's homework was decimal points multiplication/division with 10,100 and 1000.

I am explaining her with the rule that if multiplying then then decimal point hops towards right and if it is division then the decimal point hops towards left.

Anything wrong ? May be it is me making it tricky for her.
Guest55
Posts: 16254
Joined: Mon Feb 12, 2007 2:21 pm

Re: Year 4 struggling with decimals

Post by Guest55 »

Decimal points never move - the digits move.

This is an important point as the place value of the digits is what changes when we multiply or divide.
mystery
Posts: 8927
Joined: Tue Jul 21, 2009 10:56 pm

Re: Year 4 struggling with decimals

Post by mystery »

workingmom wrote:Hi all you helpful people out there

Yesterday night (again after a long day at school and swimming) my DD and I had a bit of a struggle with decimals.

She is currently in Year 4 and have just started with Decimals. I am helping her out in understanding the ordering and how multiplying and dividing them with 10, 100 and 1000.
Things became tricky when some of the questions we encountered had a a decimal number conversion from kg to g and then m to km.
Both concepts when discussed separately, she knew i.e the multiplication/division of decimals and conversion, but when both of these came together, she didnt quite get them.

Wonder if other mums are seeing the same of their kids in year4 and how are they helping them ?
Yes. Maths at school seems to be a mess for us right now too. And yes, you never get to find out what they were taught or how they were taught it at school so you're left blind with the homework. Not that we get any year 4 homework as complicated as this! Top group, 4c at end of year 3, but homework is addition and subtraction if there is any, and a note to do some timestables revision from time to time.

You could try asking the teacher if she could let parents know with each homework what they have been taught that week and how. You might be pleasantly surprised. But you might not be. Don't know. Our school is like GCHQ.

Show her how the digits move when you multiply and divide and then yes, the decimal point moves the opposite way indeed!

Then she needs to maybe do some more practical things to see that a measurement in centimetres results in an answer which is 100x the same measurement in metres ... so then she'll be able to think at the beginning of each problem "now do I divide or multiply" and explain why ... important to pause and do this thinking before launching into the arithmetic.
Guest55
Posts: 16254
Joined: Mon Feb 12, 2007 2:21 pm

Re: Year 4 struggling with decimals

Post by Guest55 »

mystery - decimal points don't move - the digits move.
mystery
Posts: 8927
Joined: Tue Jul 21, 2009 10:56 pm

Re: Year 4 struggling with decimals

Post by mystery »

Oh goodness G55, I'm not thick! Yes the digits move, but once a child has understood that it's a good deal more accurate just to shunt the point along in the opposite direction, particularly if you are dealing with a great long string of numbers e.g. 89623.09872 --------- oh I know you are now going to say they won't be given numbers like this at primary school. No, they won't, but if they understand it and have been taught it well they should be able to multiply and divide by 10, 100, 1000, 10000 etc whatever the number.

What I meant to say, was show her how the digits shift, in which direction and by how many places, when you multiply by 10, 100, 1000, 10000 etc etc but I missed some words out.
Guest55
Posts: 16254
Joined: Mon Feb 12, 2007 2:21 pm

Re: Year 4 struggling with decimals

Post by Guest55 »

Mathematicians never move a decimal point .... no matter how large the number.
mystery
Posts: 8927
Joined: Tue Jul 21, 2009 10:56 pm

Re: Year 4 struggling with decimals

Post by mystery »

Oh right. I'll do a quick survey of a few maths professors tonight then. They'll probably say they scarcely use numbers anyhow ... it's arithmetic.
yoyo123
Posts: 8099
Joined: Mon Jun 18, 2007 3:32 pm
Location: East Kent

Re: Year 4 struggling with decimals

Post by yoyo123 »

We stress that the decimal points don't move at primary, so it is best to keep with the same way as the school wherever possible. This isn't new btw and does help with the understanding of place value.

I find this

http://www.skillsworkshop.org/resources ... lue-slider" onclick="window.open(this.href);return false;

very useful.

I make it from card (the back covers of A4 ruled pads are perfect) and have used them for the last 6 years. The children find them very useful and it does give a very visual demonstration.
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