singaporemath in action 3

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mathematical problem solving

Yeap Ban HarNational Institute of Education

Singapore

www.banhar.com

Session 3

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Problem 1How many paper clips are there in the box on your table?

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Problem 2Arrange the cards so that you can do the card trick shown to you.

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Problem 3How many three-fourths are there in 1 whole?

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How many three-

fourths are there in one

whole?

Ateneo Grade School, Manila

Problem 4Give a 3-digit number and a 2-digit number so that the difference is 3.

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-

3

Problem 5Use one set of digit tiles to make a correct addition sentence.

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+

Problem 6Use one set of digit tiles to make a correct addition sentence.

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+

Problem 7Use one set of digit tiles to make a correct multiplication sentence.

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x

Solutions from Participants• 45 x 2 = 90 • 18 x 2 = 36 • 16 x 3 = 48 • 43 x 2 = 86• 13 x 4 = 52• 17 x 2 = 34• 14 x 5 = 70• 26 x 3 = 78• 15 x 6= 90• 29 x 3 = 87

• 34 x 2 = 68• 12 x 5 = 60• 13 x 6 =78• 35 x 2 = 70• 48 x 2 = 96• 16 x 5 = 80• 12x 8 = 96• 15 x 4 = 60• 19 x 2= 38• 27 x 3 = 81

• 15 x 2 = 30• 17 x 4 = 68• 12 x 7 = 84• 19 x 3 = 57

Why are there so few odd products?

Shaping Maths Coursebook 4A

Two Numbers

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614

2 units 6144 units 1228

The sum of the two numbers is 1228.

Shaping Maths Coursebook 4A

Boys & Girls

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342

2 units 342 – 50 = 2921 unit 292 ÷ 2 = 140 + 6 = 146

There are 146 Primary Four boys.

boys

girls 50

Shaping Maths Coursebook 4A

Stamps

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1775 + 85

After

1 unit 1860 ÷ 4 = 465

At first, Samuel had 465 – 85 = 380 stamps.

Ravi

Samuel

Shaping Maths Coursebook 4A

Keys Grade School, Manila

1860

1600 260

240 20

George Polya’sProblem-Solving

Model• Understand

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• Plan• Do• Look Back

Think!Can you recall each of the four problem-solving phases when we were solving the problems in the last hour or so?

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HeuristicsWhat are some of the methods used to solve the problems? Make a list of heuristics used.

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