Maths - bar method -stumped

[srw]

thanks - now I know what the bar method is, it looks like you need to solve the problem using simple algebra then draw a to-scale "bar" to represent each answer.

Not sure how this helps though

It doesn't. It appears to be based around the idea that maths isn't actually a precise, conceptual framework based around proof by deduction and abstraction and instead is a branch of engineering. It won't teach maths at all - it will teach ready-reckoning.

It's a good thing we don't have children, because any teacher that tried teaching our putative offspring to solve simultaneous equations by measuring pictures would be very forcibly, and angrily, re-educated.

 

[LocalLad]

this sort of thing bugs me too...too much teaching by tricks.

my 7 y-old was given a calculation along the lines of: 90 / 3 = ?
the teacher told them to "remove the zero, do the division then add it back on". What BS. Why not teach them to do it properly - starting at the left, and taking remainders forward. their method works for one circumstance - where the 9 is divisible by 3. It falls down with 70 / 3.

 

[nickyboy]

Singaporean children achieve much better results in Mathematics than those in UK so perhaps we should not be so dismissive of their methods?

LIke some others here, I can solve the problem algebraically. But I suspect the majority of people in UK couldn't. Maybe other techniques would be more effective and those of us who can handle the algebra should be open to other techniques that could help others

 

[jonny jeez]

[QUOTE 4494341, member: 45"]Just spent ages with the boy on this. I can't even get to an equation, let alone work it out using the bar method. I did A-level maths all those years ago, and he's in year 10. Any maths experts on here?...

Lee Suan, Amir and Prasad shared £1080. Amir received £288. The difference between Prasad and Amir was double that of the difference between Lee Suan and Amir. In what ratio did they split their money, and how much did each person get?[/QUOTE]
lee threatens Sue, Amir and Prasad with an iron bar and takes all the cash.

Lee gets the higher ratio.

#Streetmathsinnit

 

[oldfatfool]

this sort of thing bugs me too...too much teaching by tricks.

my 7 y-old was given a calculation along the lines of: 90 / 3 = ?
the teacher told them to "remove the zero, do the division then add it back on". What BS. It falls down with 70 / 3.

#
No it doesn't (7/3)x10 is still the same as 70/3

 

[subaqua]

#
No it doesn't (7/3)x10 is still the same as 70/3

and 7/3 is what exactly ? its a whanky method done by lazy teachers. ( that was mrs Sub making me type that)

 

[srw]

and 7/3 is what exactly ? its a whanky method done by lazy teachers. ( that was mrs Sub making me type that)

7/3 is 2 and a third, or 2.333....

Every method that you can think of for calculating 70/3 is identical to dividing 70 by 10, then dividing by 3, then multiplying by 10. It's maths, innit.

 

[nickyboy]

7/3 is 2 and a third, or 2.333....

Every method that you can think of for calculating 70/3 is identical to dividing 70 by 10, then dividing by 3, then multiplying by 10. It's maths, innit.

Quite. And I'm all for teaching kids how to do +, -, x, / in a way that replicates how someone who is decent at mental arithmetic would approach a problem

For 70/3 I would do 7/3 and then multiply it by 10 in my head

 

[subaqua]

7/3 is 2 and a third, or 2.333....

Every method that you can think of for calculating 70/3 is identical to dividing 70 by 10, then dividing by 3, then multiplying by 10. It's maths, innit.

i know that and you know that and Mrs sub knows that, but they haven't taught them any way of getting the 2 and 1/3 have they.

i struggled with maths in my early primary years due to a whanky lazy teacher. My parents knew how to get the answer but were not teachers by any sense of the word so just confused me even further.

thankfully the next few years after i had a good teacher.


give a man a fish/ teach a man to fish, innit .

 

[srw]

Quite. And I'm all for teaching kids how to do +, -, x, / in a way that replicates how someone who is decent at mental arithmetic would approach a problem

For 70/3 I would do 7/3 and then multiply it by 10 in my head

To be honest, for 70/3 I'd probably recognise that 69/3 is exactly 23, and then add a bit - or a third if I was thinking a bit harder.

 

[subaqua]

Quite. And I'm all for teaching kids how to do +, -, x, / in a way that replicates how someone who is decent at mental arithmetic would approach a problem

For 70/3 I would do 7/3 and then multiply it by 10 in my head

and how do you do the 7/3 . explain to us all the steps involved ......

 

[srw]

i know that and you know that and Mrs sub knows that, but they haven't taught them any way of getting the 2 and 1/3 have they.

If someone's trying to work out 70/3 without first knowing how to calculate 7/3 (take 3 away from 7 until there's nothing left - twice), then heaven help them.

 

[Andy_R]

The bar method was first developed in 1970's comprehensive schools. Teachers would go to the bar at lunchtime to enable them to continue not teaching in the afternoon. A whole generation of pupils didn't learn a thing in any afternoon lessons thanks to the bar method.

 

[nickyboy]

and how do you do the 7/3 . explain to us all the steps involved ......

Well I just know it, like I know that 4 x 5 = 20 without having to work it out

I appreciate what you're driving at. Most people to calculate 7/3 would get 2, then use the 1 remainder to get the 1/3. If the sum was a bit more difficult I would do this too. But the question is should we use mathematical processes that replicate how we actually handle mental arithmetic

For 70/3 nobody who is good at mental arithmetic would calculate it using the "division" method

 

[LocalLad]

wow, didnt expect that level of debate! For my little one, the answer would be 20 given the way they've been taught maths...as soon as you start allocating the remainder then you're doing the division method anyway. As a point of order, they weren't taught to divide by zero then multiply by zero - just to "take the zero off". the reason they're taught this way is that the work sheets the school bought in pretty much always have one of those calculations on it, so by teaching them one method, the kids will all get the sheets right so the teacher can claim teaching excellence..