Tuesday, March 31, 2015

March 31 on Apples

How many such plates can be prepared using 45 green apples and 45 red apples?

Which of these is correct?
45 divided by 4 = 11 remainder 1
45 divided by 5 = 9
90 divided by 9 = 10

Sunday, March 29, 2015

March 30 on Public Housing

Calculate the percentage increase in the number of public flats since 1959.

Friday, March 27, 2015

March 27 on Politics

Lee Kuan Yew had just passed away and the country is in mourning and there news is filled with the life of the great leader.

"The People's Action Party had just swept the 1959 Legislative Assembly General Election, winning 43 out of 51 seats. It was the first time the PAP, which up till then was an opposition party, had come to power." | Source Straits Times

How many percent of the seats was won by PAP in 1959 General Election? Explain how the caluxlation can be done easily without the use of a calculator.

Thursday, March 26, 2015

March 26 on Queue

How many persons are in front of you for you to have to stand in line for eight hours to pay your last respects?

Wednesday, March 25, 2015

March 25 on Exercise

Mr Lee Kuan Yew liked to exercise. Some politician got slammed for dedication his exercise to Mr Lee Kuan Yew. Here is one on exercise.

Ben has an hour of exercise with his trainer. He has to complete ten exercises. Each exercise is to be done three repetitions, each time takes 1.5 minutes including rest time. Can he complete all these in an hour? What is the latest time he needs to arrive to finish all these exercises by 7 p.m.?

Sunday, March 22, 2015

March 23 on Lee Kuan Yew

Remembering Lee Kuan Yew.

(1) How old was he when he passed away?

(2) Looking at the line graph, what can you say about GDP per person for Singapore since 1960?

Thursday, March 19, 2015

March 20 on Private Club

In Singapore, the ubiquitous hawker centres exist alongside very atas members-only establishments clubs where "a vote at a special general meeting on Monday came out 206 to 95 in favour of counting a member's nationality at the time of joining". 

The maths Is mind-boggling, so are the concerns of the members. You see, in this club "only 51% can be of any one nationality" (they got use only correctly here anot? Standard English - Is only used correctly here?). Then they discovered that, what a surprise, 55.5% of the members are Singaporeans (duh, the club is in Singapore!). That breached a cardinal rule. After much investigation, the mystery was resolved. 292 members were not Singaporeans when they joined but later took up citizenship. With the result of the voting on Monday, these 292 members "went back to retaining their original citizenship at the club" (lol) "This move brings the number of Singaporean members down to 48%, meaning there is now space for 112 more - from a waiting list of 1,301 Singaporeans - to sign up" (lol). Told you it is one-boggling. And parents complain we give problem like 'Ali has four-fifths as much money as Sam in school.' You find more complex stuff on Straits Times. Maths Problem | How many members does this club have?

Oh! By the way the club increased its entrance fee from $35,000 to $50,000 for new members. This gave the club  a $5.6 million windfall. Maths Problem | How many suckers, I mean new members, paid the new fee?

Sorry ah if you are a member and think I am making fun of you. I am.   

Those who can, join the club. Those who can't, make up maths problems about it. 

March 19

Tuesday, March 17, 2015

March 18 on Bread

How much does it cost to buy (a) 24 (b) 25 and (c) 26 pieces?

Note for Parents | Practice is not doing repetitive exercises. Practice is to solve one problem and its variations. The three tasks are not repetitive but get students to think about different aspects of the problem. 

Monday, March 16, 2015

March 17 on Private Property

These are actually public housing in Singapore - the ubiquitous HDB flats which the majority of Singapore residents live in. 
There were 382 apartments sold in January, a modest 2% gain over January's figure. 

How many apartments were sold in January? (Basic)

The figure 2% has been rounded to the nearest 1%. Find the possible number of apartments sold in January. (Advanced)

Another source of word problems in the real-world context is the mass media. I adapted a sentence from Straits Times (17/3/2015 p.1) for the word problem above. 

Sunday, March 15, 2015

March 16 on Private Schools

In few places around the world are public schools preferred to private schools even among affluent families. Singapore is one of them. 
In 2013 SIM's enrollment hit a high of 23,000, with 20,000 locals. Last year, the number fell to 21,500, with 18,000 locals. 
What is the percentage decrease of local students in SIM? Can the decrease be expressed as a fraction? State a unit feaction that can be used as a good estimate for the percentage decrease.

The reason is because there are now more places in the public universities. SIM is a private school. 

Saturday, March 14, 2015

March 15 on New Paper

In a newspaper report, one of the interviewees said she was earning $1500 before getting another job that paid her $4000 which gradually increased to $5000. 

Calculate the percentage increase each time.

In an international scale to measure achievement, students who can do this is in the second category of four categories. Students in this - called Intermediate - are able to use calculation in one-step situations.

Friday, March 13, 2015

March 13 on Snacks

How many pieces of this Chinese New Year snacks are needed if Mrs Yeap needs 20 bottles of the snack to give to her children and grandchildren?

The use of visual is another way to write innovative test items. In this case students need to estimate and possess a sense of space in addition to the ability to compute to complete the task.

March 12 on Percentage

I used this as an anchor tasks for Grade 7 students in Westport Public Schools. Percentage change is a common concept in the media.

Spiky saved $200. Curly' savings was 4/5 Spiky's. The next year, Curly saved 20% more. Find how much was Curly savings the next year.

What other fraction and percent can result in Curly having $192 as her savings the next year?

This is what-if problem posing (Brown & Walter - The Art of Problem Posing).

March 11 on Apples

How many such plates can we get using six dozens green apples and twenty plates?

Students need to consider if the apples or the plates is the limiting factor. Students haveto think things through and not just identify a relevant operation and perform the computation.

Friday, March 6, 2015

March 5 on Airport Math

I checked in two bags. How heavy us each?

What other Mathematics based on air travel can you think of?

March 3 on Things

A costs $168.
B costs $75 more than A.
C costs $300.

What could these things - A, B and C - be?

What are some questions that can be answered using the given information? 

This is one strategy to help students connect real-life knowledge with textbook problem (the problem is taken from Math in Focus 2).

March 4 on Juice

The larger bottle is 946 ml. The smaller on is 450ml. The larger one contains five and three-fourths apples, 1 banana, 1 kiwi, 3/4 mango and 1/6 pineaaple among other things. The smaller one contains two and three-fourth apples, 1/2 banana, 1/2 kiwi, 1/3 mango and 1/12 pineapple.

Is the proportion the same?

Wednesday, March 4, 2015

March 2 on Eggs

This problem is a common Primary 5 problem.

Sid had some eggs. After using one-fourth of them to make cakes and m of the remainder to make chawan mushi he had 60 eggs left. 

How many eggs did he have at first?
Solve the problem for m = one-third, one-sixth and one-fifth.

I did this lesson at Weston Internediate School today. 

The photograph was taken at The Snake Temples and the eggs were offerings made by devotees to the snakes in the temples.