Thank u!

1 + 2(0), 3 + 2(1), 5 + 2(2),...

Ban Har Yeap are you some author of assessment books? Your name sounds familiar

1,5,9, . . . a=1 b=4 U9=a+8b =1+8*4 =1+32=33

Mike Tan i have not written any 'assessment book'. Maybe your children's secondary textbook. Or it us just a common name.

Sorry, i think it should be the textbook.

Haven't taught secondary maths in a while now

Hi Ban.. Do u mind explaining in primary way? This is a worksheet from my P3 child. Need to explain to her.. May I ask what is the final answer?

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4 x figure number - 3

Fig 1 + 0 = 1 Fig 2 + 3 = 5 Fig 3 + 6 = 9 Fig 4 + 9 = 13 . . . Fig 10 + 27 = 37 To get 27, (10-1) x 3 = 27

477 - 1 = 476 476/4 = 119 119 + 1 = 120

In the first place, let students discover the pattern such as 1+4+4+4+...... (a) 1+4+4+4+4+4+4+4+4+4=37 (Or 40-3=37) (b) consider either 477-1 or 477+3. Ask "how many 4s make 476" (119), or "how many 4s make 480?" (120). So the answer is 120.

I saw questions similar to this in a p4 assessment book.

(a) Fig 10 ------ 9 × 2 + 9 × 2 + 1 = 37 (b) 477-1= 476 476÷2÷2= 119 119 + 1=120

Yes, 37 and fig 120 are the answers

How Can a primary 3 child do this problem?

Hi, we can do this easily by 1st observing that there each subsequent figure adds 2 X both vertically and horizontally each time. So 2nd figure adds 2 X vertically and horizontally to 1st figure while 3rd figure adds (3-1)x2 X vertically and horizontally to 1st figure and 4th figure adds (4-1)x2 X vertically and horizontally to 1st figure, so 10th figure adds (10-1)x2 X vertically and horizontally to 1st figure. Total number of X in 10th figure = 9x2x2 +1 = 37

477 = 476 + 1 = 238x2 +1 = [(120-1)x2]x2 +1. So clearly the answer is 120

Basically the aim of this question is for students to be able to generalize the patterns after trying out a few examples.

It's basically adding twos onto each end

I think

I started the model method in the 1980s. Many people continued to grow it. Among them are Hector Chee, Fong Ho Keong, Yeap Ban Har and Liu Yueh Mei, especially Dr Yeap who has done so much for the method. I really think that they are great.

4 times 10 equals 40 plus 1 equals 41. 447 divide by 4

Y gave 18/2 = 9 to S. 56 - 9 = 47

Concrete -- If we take 2 paper strips, one longer than the other, and then try to make both equal, we will end up tearing the 'extra' off the longer piece, divide this 'extra' piece into half to share between the 2 strips to get equal length. This means that half of 18 will have to be give to Serene for them to have equal number of postcards. Working backwards from Serene, 56 - 9 = 47. So Serene had 47 at first.

Gave---> 18 divide by 2=9 At first----> 56-9= 47

120/2 = 60 60+15= 75

Thank u!

Must we draw model for this type of questions?

For students to make sense of the problem and to decide how to work out the solution, it would be better to draw models to represent the problem. Otherwise, students might understand our solutions but may not know how to work out on their own and develop their problem solving skills.

Thanks so much

Of cos once the student is able to visualize and work it out without drawing, then that's good... That's what we want...

Sometimes not sure wat model to draw

If you post questions with the attempted solutions, we will be happy to help by taking a look at your child's attempt and pointing out what's done correctly and where there might be mistakes. It's more beneficial for your child's learning that way.

For this question we can start with the model of what Ali has at the end and work backwards. And we ask -- how did he get 120? What would Ben have given him to end up with 120? And continue working backwards from there...

Thanks Vei Li Soo, I will surely seek help. Thanks for being so helpful to a helpless mum

Students may use the heuristic "working backward" to help them solve the problem. Staring with 120, students ask, "how did the number become 120? (After doubling). Working backward we half it to 60. Students ask again, "how did the number become 60? (After giving away 15). Working backward we get 75. Instead of drawing a bar model, we draw an arrow diagram such as ? --> 60 --> 120 75 <-- 60 <-- 120

150 ÷ 5 = 30 30 × 30 = 900

thks vm for yr help, Mike