
By: tangara (offline) Wednesday, August 03 2011 @ 09:16 PM CDT (Read 2273 times)



tangara 
Hi experts,
I hv this question from Bt Panjang Primary.
Seemingly easy but I don't trust myself so I would
like to know de solution. Tks.
The volume of water in Pond A is thrice of that in Pond B.
After 678.98liters of water was added to Pond A,
the volume of water in Pond B was 5 times de volume
of water in Pond A at first.

Junior
Registered: 07/31/10 Posts: 26





By: tangara (offline) Thursday, August 04 2011 @ 04:54 AM CDT



tangara 
Sorry I made a mistake.
De vol of water in pond A was 5 times de volume
of water in pond B.

Junior
Registered: 07/31/10 Posts: 26





By: anniechew12 (offline) Sunday, August 07 2011 @ 11:50 PM CDT



anniechew12 
Quote by: tangaraSorry I made a mistake.
De vol of water in pond A was 5 times de volume
of water in pond B.
Pond A was 5 times de volume of water in pond B
53 = 2
678.98/2 = 339.49
Pond A = 339.49*3 = 1,018.47
Pond B = 339.49

Newbie
Registered: 06/23/11 Posts: 5





By: cimman (offline) Monday, August 22 2011 @ 12:19 PM CDT



cimman 
this question is best solved using algebra. I know they don't teach algebra at this level, but knowing algebra is much easier to convert the words to mathematical equation. Basic algebra is not difficult for the child to comprehend.
A=3B  1
A+678.98=5B  2
3B + 678.98 = 5B  3
678.98 = 2B
B = 678.98/2

Newbie
Registered: 05/01/11 Posts: 5





By: saslwp (offline) Tuesday, September 06 2011 @ 01:07 AM CDT



saslwp 
It is easy to solve this algebraically, but primary students are taught to apply heuristics solving
technique to such question, using modelling method. See attached for eg.

Newbie
Registered: 09/05/11 Posts: 2





By: tangara (offline) Tuesday, September 06 2011 @ 09:41 PM CDT



tangara 
Quote by: saslwpIt is easy to solve this algebraically, but primary students are taught to apply heuristics solving
technique to such question, using modelling method. See attached for eg.
Hi saslwp,
Thanks for showing the heuristic method.
You explanation is so clear indeed that I understand the method immediately.
Thank you once again.

Junior
Registered: 07/31/10 Posts: 26





By: ZombieFreak (offline) Wednesday, September 07 2011 @ 03:33 AM CDT



ZombieFreak 
Quote by: tangaraHi experts,
I hv this question from Bt Panjang Primary.
Seemingly easy but I don't trust myself so I would
like to know de solution. Tks.
The volume of water in Pond A is thrice of that in Pond B.
After 678.98liters of water was added to Pond A,
the volume of water in Pond B was 5 times de volume
of water in Pond A at first.
Super lousy, easy question also don't know.

Junior
Registered: 10/29/10 Posts: 17





By: cimman (offline) Wednesday, September 14 2011 @ 10:26 PM CDT



cimman 
Quote by: saslwpIt is easy to solve this algebraically, but primary students are taught to apply heuristics solving
technique to such question, using modelling method. See attached for eg.
it is true that primary school students are encouraged to use hueristics. However, by the time they reach PSLE, they are expected to know basic algebra and simultaneous equation.
When they reach secondary school, maths problems will be solved through algebra and equations, heuristics will not come in at all. No one is going to be drawing boxes to solve problems in secondary school.
I'm always puzzled why MOE will teach students a heuristic system that when they move on to Secondary school will be thrown away. It's a throw away skill. I'll rather they spend more time learning algebra at an earlier age and have something they can use till Secondary school and beyond.
As you've said, it is easy to solve it algebraically, so why don't the schools teach something easy which can be used beyond the PSLE level ?
actually, they have tried to sneak in algebra at a very early age, ie. those (star + square + circle = 35, star + square = 10, what is value of circle ?) type of questions. That's definitely algebra disguised as shapes.
I really don't understand our education system. Why is there a mindset that students cannot learn algebra till PSLE ? I really don't think our students are not capable of learning algebra at an earlier age.
While modeling is good for solving certain kinds of problems, when the numbers scale up, imagine drawing 20 or more boxes. Also the motor skills of children needs to be taken into account. They can't draw a straight line, much less neatly aligned boxes.

Newbie
Registered: 05/01/11 Posts: 5





By: cimman (offline) Wednesday, September 14 2011 @ 10:42 PM CDT



cimman 
Quote by: ZombieFreakQuote by: tangaraHi experts,
I hv this question from Bt Panjang Primary.
Seemingly easy but I don't trust myself so I would
like to know de solution. Tks.
The volume of water in Pond A is thrice of that in Pond B.
After 678.98liters of water was added to Pond A,
the volume of water in Pond B was 5 times de volume
of water in Pond A at first.
Super lousy, easy question also don't know.
not everyone is born with a mathematically inclined mind. Some people are just better at languages, others at Maths, others at Science. No need for insults here.

Newbie
Registered: 05/01/11 Posts: 5



