Q&A - P3 Math

[tianzhu]

lizawa:

[quote]I need to know how many methods are there to solve problem sums for Pri 3? If my son does not use any of the methods but get the answer right, would he be penalised?

Don't worry if your son is doing well. Based on MOE's statement sometime back (published in the papers), a child will not be penalized no matter what method he uses for PSLE exam. The markers however, will allocate marks for working, so just make sure his steps and working is clear. If the child just gives an answer without working for problem sums, he only gets the mark for the answer and not working.[/quote]http://www.moe.gov.sg/media/forum/2007/20070217_print.htm
17 Feb 2007
Different Approaches Taught for Mathematics Techniques
1.\tMr Lim Boon Tong had sought clarification on whether mathematics techniques like algebra, other than the model drawing method, could be used in the Primary School Leaving Examination (PSLE) Mathematics. (“Can algebra be used to solve PSLE maths problems”, The Straits Times, 12/2).
2.\tThe model drawing method is a powerful approach for problem solving and learning mathematical concepts. By drawing models, pupils can represent the mathematical relationships in a problem pictorially. This helps them understand the problem and plan the steps for the solution.
3.\tThe pictorial form also helps pupils visualise what could otherwise be abstract concepts. In this way, model drawing supports the learning of fractions, ratio and percentages. Pupils will find model drawing useful when they solve problems involving these concepts in Primary Five and Six.
4.\tThe model drawing method is thus a developmentally sound approach for young children. It is recognised internationally as an effective way for young children to learn problem solving and to have early exposure to algebraic concepts. At Primary Six and Secondary One, pupils can draw upon their earlier experience of using models to help them understand algebraic relationships in problems.
5.\tOther than the model drawing approach, pupils are also taught different problem solving methods. They are encouraged to try different approaches and have the flexibility to choose the method that works best for them in solving the problems. They are also encouraged to present their solutions clearly so that these can be understood.
6.\tWhile pupils are not required to use algebra to solve word problems in the PSLE Mathematics, they are also not restricted to the use of any one particular method. In the marking of PSLE Mathematics, all mathematically correct solutions are acceptable and there is no loss of marks if a correct algebraic method is used.
7.\tWe thank Mr Lim for his feedback.
Ho Peng (Ms)
Director, Curriculum Planning and Development
Ministry of Education
Tan Yap Kwang
Chief Executive
Singapore Examinations and Assessment Board

[ck123]

I totally agreed that Maths is not our old time Maths.


My boy bring back HW last week and guess what the questions is not difficult but :shock:

Questions : You are given 2 containers. Capacity of Container A is 4L and Container B is 7L. How can you measure out 5L of water?

It looks more like a logic questions than a maths questions. I have to use 2 containers, goes to the tap, physically pour the water in and out of the containers to show my son. And the last part waas tougher for him \"HOW TO PEN IT DOWN AS ANSWER???????? \"

So we need some language here too........ : :roll:

[corneyAmber]

ck123:

I totally agreed that Maths is not our old time Maths.


My boy bring back HW last week and guess what the questions is not difficult but :shock:

Questions : You are given 2 containers. Capacity of Container A is 4L and Container B is 7L. How can you measure out 5L of water?
It looks more like a logic questions than a maths questions. I have to use 2 containers, goes to the tap, physically pour the water in and out of the containers to show my son. And the last part waas tougher for him \"HOW TO PEN IT DOWN AS ANSWER???????? \"

So we need some language here too........ : :roll:

is this the answer?
pour 7ml water into the 4ml container,
then 3ml left in 7ml container.
then 4ml container pour half away, left 2ml...
pour this 2ml back into 7ml container that contains 3ml to get 5ml.

another way more accurate is:
pour 7ml water into the 4ml container,
then 3ml left in 7ml container.
empty the 4ml container n pour the 3ml into it
mark the 3ml level on the 4ml container
fill 4ml container n pour into 7ml container
fill second time 4ml container n this time pour only water above marking into the 7ml container to make 5ml.

[ck123]

Answer:


First, Pour 4L of water into 7L container.
then fill up 4L container again and pour till 7L container full and so the 4L container would have 1L of water left. Then empty the 7L container and pour the 1L of water from the 4L container to the 7L container. Fill the 4L container again and pour to the 7L container. So now the 7L of container would have 5L of water (1L + 4L).

There is no marking or estimation or half so above is the answer.

See I don't think I can pen it down properly so how to expect my son to do it????

[corneyAmber]

can la...with practice the kids can do it cos it is like a game. sometimes we worry too much.


i just thot of this solution before i read this...cos math is very precise. :lol: but the fun part is in practice we can try 3 different methods n in real life we may need to do that during baking sometimes. thanks for the answer.

[ChiefKiasu]

Yuh… came across the container question before.


Here’s another one from Catholic High. It goes something like this:

Charles and Daniel have the same amount of money. After Charles received twice the amount of money he had and Daniel spent $8, Charles now has 4 times the money Daniel has.

How much did Daniel have at the beginning?

Again… modeling only hor - no cheating with algebra!

[corneyAmber]

ChiefKiasu:

Charles and Daniel have the same amount of money. After Charles received twice the amount of money he had and Daniel spent $8, Charles now has 4 times the money Daniel has.


How much did Daniel have at the beginning?

Again... modeling only hor - no cheating with algebra!

___________
1 unit=u (Charles at first=Daniel at first)

______
u-8 (Daniel spent 8 dollars)

___________ ____________
1u 1u (Charles after it doubles)

______ _____ _____ ______
u-8 u-8 u-8 u-8 (Charles 4 times of Daniel after D spent)

So 4[u-8] = 2u
4u - 32 = 2u
2u = 32
u = 32/2 = 16

So Charles at first = Daniel at first = $16

[David Koriadi]

Hi ChiefKiasu,


This question is from Catholic High School (Primary) P3 CA2 Maths 2007.
Being a newbie,I don't know how to post image in this forum. Anyway the answer is $ 32 via MD method.

Before
Charles U + 8 + U + 8 + U + 8
Daniel U + 8

After
Charles U + U + U + U
Daniel U

4U -> 3U + 24
1U -> 24

Daniel had at the beginning -> U + 8
= 24 + 8
= $ 32 Ans

Is this the correct answer ?

[wwcookie]

ks2me:

1 unit=u (Charles at first=Daniel at first)


______
u-8 (Daniel spent 8 dollars)

___________ ____________
1u 1u (Charles after it doubles)

______ _____ _____ ______
u-8 u-8 u-8 u-8 (Charles 4 times of Daniel after D spent)

So 4[u-8] = 2u
4u - 32 = 2u
2u = 32
u = 32/2 = 16

So Charles at first = Daniel at first = $16

I got the same ans as ks2me :lol: Is this modeling mehod?

[ChiefKiasu]

ks2me:

___________
1 unit=u (Charles at first=Daniel at first)

______
u-8 (Daniel spent 8 dollars)

___________ ____________
1u 1u (Charles after it doubles)

______ _____ _____ ______
u-8 u-8 u-8 u-8 (Charles 4 times of Daniel after D spent)

So 4[u-8] = 2u
4u - 32 = 2u
2u = 32
u = 32/2 = 16

So Charles at first = Daniel at first = $16

Sorry ks2me and wwcookie... both of you fell into the same trap as I when I first did the question. Charles did NOT just DOUBLE his sum of money. He TRIPLED it. Read the question again :).

Also, you were using algebra towards the last step. Naughty naughty