Q&A - P3 Math

[teh_oh]

tianzhu:

teh_oh:

Is the answer
25 Big Fish and 75 Small Fish?
(while i still scratching my head, my child gave me this answer.......but he said he use trial and error. :oops:)

Hi

Your answers are correct.

Best wishes

Hi Tianzhu,

Thanks! Anyone can post the workings? My child solved it using trial and error.

Looking forward....

[tianzhu]

teh_oh:

Hi Tianzhu,


Thanks! Anyone can post the workings? My child solved it using trial and error.

Looking forward....

Hi teh_oh and concerned1970

A quick one first using “Make a Supposition”. I’ll try to put up the solution in tabulated form using PowerPoint at a later time if there is a need.

Suppose there were 100 big fish.

We have 100B ----- $300 (100B ---- 100 big fish, and 100*3 ------$300)

Consider a group of 3 small fish @ $1

97B and 3S ------- $292 (97 big fish and 3 small fish ----- 292)

300 – 292 ------8

So, every increase of 1 group of 3 small fish will lead to a drop of $8.

300 – 100 -----200
200/8 ------25

We have 25 groups of 3 small fish, which is 75 small fish.

Hence we have 25B and 75S.

Best wishes

[teh_oh]

Thanks Tianzhu.


Can't believe this is the standard P3 questions nowadays.

[tianzhu]

Hi concerned1970


Good Morning

Here's the solution for your \"mangoes and oranges\" question in diagram.

I've drawn picture of mangoes and oranges in my solution, but in examination, a student may draw circles and squares or circles in different colours for the representation. You don't need to draw perfect circles or squares, just some neat diagrams will do.

As usual, I’ve shown more diagrams to show the flow of events. Once you are able to see the logic behind the solution, you may reduce the number of diagrams or solve this question without MD in the future.

Hope this helps.

Best wishes

http://farm6.static.flickr.com/5140/5536110666_92946a6e2a_z.jpg\">

[tianzhu]

teh_oh:

Thanks Tianzhu.


Can't believe this is the standard P3 questions nowadays.

Hi teh_oh

Good Morning.

Such questions are common in P3 and P4. I remember seeing them a few years ago when my boy was in P3/P4.

This question is a variation from the usual” Counting heads and legs” questions.

Q1) Xie Ming Ming has 6 chickens and cows in a farm. There are 16 legs altogether. How many cows are there?

Q2) Masha visited a farm where he saw some cows and ducks. There were 75 of them. He then counted the legs of the animals and found that there were 220. How many animals of each type were there in the farm?

For the \"Big and small fish question\", you need to increase/decrease in groups of three.

For lower primary, it’s appropriate to use GC with calculated guesses as the numbers are usually not too big.

I remember my boy started from drawing simple diagrams like circles with two or four lines to represent legs, GC and then moving to “Make a Supposition” to solve such questions.

This solution is for a P6 question, you may apply the same logic to solve the \"Big and small fish question\"as well. You’ll get the right combination at the first try.

http://farm6.static.flickr.com/5052/5456348000_75a99120c9_z.jpg\">

Here’s another two similar type of questions.

Q1) Jia Ling paid $25 for 35 pens and pencils altogether. The pens were sold at $2 each and pencils were sold at 3 for $1. How many pencils did she buy?

Q2) There are 85 bowls of Bak Chor Mee for 80 people. Each adult eats 2 bowls of Bak Chor Mee and every three children share 1 bowl of Bak Chor Mee. How many adults and children are there?

Hope this helps.

Best wishes

[teh_oh]

Hi Tianzhu,

Thanks for taking the time to answer our questions.

I was actually quite concerned when reading the few questions posted by concerned1970 as my child (and myself) has not been exposed to such questions (to my knowledge) yet. After getting him to try the questions, I was quite surprised that my child can answer some of the posted questions as I have undermined his ability (his knowledge of models is more powerful than mine as I struggle to learn alongside with him).

However, we (my husband and I) are still stunned by your explanation of the 'fishes' question as to how to explain the following:-

tianzhu:

So, every increase of 1 group of 3 small fish will lead to a drop of $8.

300 – 100 -----200
200/8 ------25

We have 25 groups of 3 small fish, which is 75 small fish.

My husband said something about 200 being the variable. I don't know what he is talking about. :oops:

Will study your latest input again. Many thanks. You are a gem.

[tianzhu]

teh_oh:

Will study your latest input again. Many thanks. You are a gem.

Hi teh_oh

You're welcome.

First thing first, is your child in P3 or P4?

Yes, children do sometimes surprise us with their abilities to see “simplicity’ behind answers.

The world is full of surprises, sometimes they also can be off form in major examinations.They may also surprise us with their less than expected results.

World Cup 2010 taught us valuable lessons. Players that are expected to shine didn’t do too well and countries expected to win performed below par.

When dealing with primary maths, my take is to see them through the eyes of our young ones.

Since we are in the KSP forum, adopt the KS way.

Keep (in) Syllabus
Keep (it) Simple.
Keep (it) Short.

The \"Big and small fish question\" is quite a unique one, in the sense the number of fish is equal to the value of fish (100).This makes it easier to arrive at the answer.

Study the solution on the P6 question, if you still need more information on the “Big and small fish question\", please let me know.

Best wishes

[concerned1970]

Tysm Tian_zhu! It always gives me a BIG heahache when comes to Math. U're a great and wonderful dad who's willing to spend time to do the revision with yr son. Not all men like u! It's not easy.

[tianzhu]

concerned1970:

Tysm Tian_zhu! It always gives me a BIG heahache when comes to Math. U're a great and wonderful dad who's willing to spend time to do the revision with yr son. Not all men like u! It's not easy.

Hi concerned1970

Good Morning.

You're welcome.

My eyes were washed with tears as I read your post.
Tears are easy to erase with tissue papers, but how do I erase the pains from my heart?

What choice do I have?

As you are aware of, Maths enrichment courses do not come cheap. I am a victim of circumstances, a \"money not enough\" dad who cannot afford my kid this avenue.

So I started to get more involved in his Maths during the second half of P5 and PSLE. At the very least, what I could offer was to help him to break down the problems into manageable steps when he encountered difficulties.

But, it’s not easy to revise with your own kid, sometimes you tend to shout at him when the going isn’t smooth. I must confess, I’ve shouted at my boy during times of frustration. Boy, daddy apologises for the unnecessary outbursts.

I wish I had deeper pockets.

世界上所有的爸爸都是一样的,they would do the same thing if given similar situation.

Best wishes

[tianzhu]

concerned1970:

Is there any other method to work out this pb sum besides guess and check method?

Hi concerned1970

Good Morning.

Yes, you can solve it in other ways besides GC.

But for P3, I think using GC with calculated guesses is quite appropriate as the numbers are not too big.

I think there are about eleven problem solving heuristics in primary maths syllabus (if I remember correctly).

If you are keen to look at alternatives, you may look at 1) Draw a diagram/picture 2) Make a Supposition, where you apply logical reasoning and 3) algebraic and solve by pictorial method.

But, I am not suggesting the third method at this moment, maybe wait until he /she is in upper primary.

Guess and Check or sometimes called Trial and Error is one of the common and simplest problem solving strategies in primary maths.

Some may say that it could take a number of guesses and is time consuming.

To use GC effectively, students need to make calculated guesses and keep a record or tabulate their trials, check their guesses against the information given in the questions and then adjust their guesses if they are wrong.

I am not a great fan of GC, I use it as a last resort. However, this method does offer a lifeline when a student runs into difficulties when experimenting with other strategies especially in examinations.

Best wishes