Monday, October 20, 2008

Singapore Math 1

I said in this post that I'd be writing more about what both Brian and Sean are encountering when doing Singapore Math. I guess I haven't done much of that, have I? Actually, I think I haven't done ANY of that!

I did start a private blog (work in progress) in June, some months after I wrote that post, but that effort quickly fizzled out. However, in the past week (since Oct 11), I've been more productive, uploading questions and solutions; I am indeed Master Procrastinator, I had Brian's birthday and my Japan trip to plan and suitcases to pack, but I'd rather work on a Math blog!

Monica's the model mum, I'm not; we're just muddling our way through. I give up really quickly with many of these questions. I'm pretty sure the 'model' in our solutions is not standard, so any help is welcome in guiding us the right way.

I've just found out from a Singapore friend that the Math test for students returning from overseas (to get into secondary schools) is as tough as PSLE. Her daughter sat for the exams this past week, and there were 2000 kids in Expo, including Chinese, Korean, Japanese, and Indian kids. I was under the impression that overseas kids would not be expected to do PSLE-standard math, since they've not exposed to the methods taught to Singapore students.

So here we go: From P5 Challenging Math, Unit 1, No 23 (Challenge question, no solution provided). Just checked, this was not the Challenge question, and there was a solution provided but it looked like algebra to me.

A basket of 6 apples and 3 mangoes weighed 1kg320g. After 4 apples and 2 mangoes were eaten, the basket with the remaining fruits weighed 760g only. If a mango weighs 20g less than 4 times the mass of an apple, find
a) the mass of the basket,
b) the mass of the apple.

My model. Okaylah, can skip reading my attempt, I'm so rubbish at this I'm confused when I see my solution now!


Algebra Method

6a+3m+b=1320 ---------------(1)
2a+m+b=760 -----------------(2)
m+20=4a -> m=4a-20----------(3)
Substitute (3) into (1) and (2)

6a+3(4a-20)+b=1320
6a+12a-60+b=1320
b=1380-18a------------------(4)
2a+4a-20+b=760
b=780-6a--------------------(5)
Substitute (4)into (5)
1380-18a=780-6a
12a=600
a=50------------------------(6)
Substitue (6) into (5)
b=780-6(50)=780-300=480

The mass of the basket is 480g
The mass of the apple is 50g
.................................
Brian's model


Is either of my model or Brian's acceptable? I'm sure there's a simpler way to present the model, so this is kind of an SOS out to all model moms and their kids out there. Thanks in advance.

Solutions may be sent to mathsingapore at gmail dot com. Thanks!

14 comments:

Anonymous said...

hi

you may want to go to this website where there are many examples with solutions to show you how models are drawn. There are also english and science topics too.

http://road-to-psle.blogspot.com/

rgds
"Model Dad" :)

Lilian said...

Thanks so much Model Dad. I'm adding that link to my blogroll pronto!

Anonymous said...

Another website where you can download all the top primary schools exam papers, from P1 to P6; and sec schools as well. The answers provided are usually correct. RGS Science answers provided are very detailed - show why some answers will get full marks, while others only half. Password to download RGS (only RGS, the rest no need for password) is abc123.

Nanyang maths papers are better than the rest - very challenging.

Have fun!

Model Dad

Anonymous said...

oops...did i mention the website? it's www.misskoh.com


rgds
model dad

Lilian said...

haha, thanks for the heads up again Model Dad; my son isn't gonna be very happy with you though! :)

Lilian said...

Er Model Dad, I just realised you didn't provide a link leh LOL!

Anonymous said...

after a while, i think your boy would prefer to do these school exam papers than assessment books, as they are closer in format to PSLE. Hey, but next year format change liao. Can use calculator...which means it's gonna be tougher. haha. because questions can be set harder, so more time needed to think, and not to spend it on manual calculations.

did you get the website? it's www.misskoh.com

Lilian said...

okay, just got your comment, xie xie!

Lilian said...

Yup, they're gonna test concepts instead of ability to calculate, so questions are likely to be even more convulated. Pengsan lah...

Lilian said...

I would love to sit the Minister of Education and his advisers down, and let them try doing some PSLE questions, see how these brainies do.

Anonymous said...

Alamak, nowadays don't have to buy these papers already huh?

Aiyoh, last time I had to go Coronation Plaza and buy or zap zap zap lor..

YY.

Anonymous said...

not just the questions would be more convoluted, but alas, there is no more time gained from doing the section A and B faster, so can devote more time for Section C. Next year, it would be a 2-paper format. With paper 1, the easier former section A & B (no calculator) - when you finish you just have to wait for everybody else, whereas now, you can proceed straight to Section C (which would be paper 2 for next year)

Lilian said...

Ai, why like that? What's the rationale of splitting the paper huh? Will be disadvantageous for those who are good at the easy questions.

Anonymous said...

Because they need to test students too on questions without the use of calculators (so that the skills would not be lost), so got to split them up.