Pair Work - Spend another 5 min to solve this question;

Class discussion - 5 min

Pair Work - Spend another 5 min to solve this question;

Class discussion - 5 min

Pair Work - Spend another 5 min to solve this question;

Class discussion - 5 min

Pair Work - Spend another 5 min to solve this question;

Class discussion - 5 min

1 Small unit :1 Big unit

4. : 5

4+4+4+5+5=22

165/22=7.5

7.5x40=300

Ans:300cm2

1u=165/11=15

10u=15 X 10=150

150 X 2=300cm2(ans)

2/4x5=10/20

22u:165

1u:165/22=7.5

40u:7.5x40=300

ans:300cm2

3/5x1/2=3/10

1/2x1/2=1/4

3/10=6/20

1/4=5/20

6+5=11

165=11u

1u=165/11=15

Total area=15x20=300

Ans=300cm2

2 out of 4=10 out of 20(bottom)

12+10=22

20+20=40

165cm2/22=7.5cm²

40x7.5cm2=300cm2

Ans: 300cm2

22u=165

1u = 165/22=7.5

Area of the square = 300cm2

Ans 300cm2

Shaded bottom:2/4=10/20

Total fraction=22/40

1/40=165/22=7.5

Area of square:7.5x40=300

Ans:300cm2

Small unit:big unit

4. : 5

   4x3=12

   5x2=10

   12+10=22

   165/22=7.5

   7.5x40=300

   Ans:300cm2

8 Big rectangle(the other half)=165x2=330 (ans)

3. : 2 : 5

4 parts- Shaded : unshaded : total

2/4=10/20

22u=165

1u=165/22=7.5

7.5x40=300

Ans=300cm2

3/5

Bottom

1/2

Common denominator =20

3/5=12/20

2/4=10/20

10/20+12/20=22/40=11/20

11/20 / 165=1/300

1cm2 =0.155 in² 1/300

300/300 =

9+9+9+9=36

36-3=33

Ans (a): 33cm

B) 198-2=196

9-2=7

196/7=28

Ans (b): 28

1x3=3

9x4=36

36-3=33

(a)ans:33cm

Q15(b)

4 rings=33

198/33=6

6x4=24

(b)ans:24

The answer is 33cm

B）198/33=6

6x4=24

The answer is 24

🐐🐐🐐

36-1-1-1-1-1-1=30

Ans:30cm

(b):198-9=189

189/7=27

27+1=28

Ans:28rings

Check for (b):

28x9=252

28-1=27

27x2=54

252-54= 198cm

distance from 1st to 4th ring : 9cm+9cm+9cm+9cm-1cm-1cm-1cm=33 cm

33cm/4=8.25 cm

198cm/8.25cm=24

Ans : (a)33cm

(b)24

9cm-2cm=7cm

7cmx4=28cm

28cm+2cm=30cm

Ans: a 30cm

Part b method 1

198cm-30cm=168 cm

168cm/7cm=24

24+4=28 (Ansb)

Part b method 2

198cm-2cm=196cm

196cm/7cm=28 (Ansb)

Answer a 30cm

Answer b 28

9-1-1=7

9+7+7+7=30

Ans30cm

b)

198-9=189

189/7=27

27+1=28

Ans28

36-1-1-1=32 cm(a)

Ans (a :30cm

B)198-9=189

189/7=27

27+1=28

Ans b :28 rings

36-1-1-1=33

(A) ans:33cm

198/33=6

6x4=24

(b) ans:24

36-3=33

B:

33/4=8.25

198/8.25=24

Ans:

A:33cm

B:24

A) 9cm x 4 = 36cm

1cm x 4 = 4cm

36cm - 4cm = 32cm

32cm + 1cm = 33 cm

Ans a: 33cm

B) 198cm x 33cm = 6

6 x 4 = 24

Ans b: 24

9cm-1cm=8 cm

9cm-2cm=7 cm

7cm+7cm+8cm+8cm=30 cm

Answer a: 30cm

(B)

198cm-8cm-8cm=182 cm

182cm/7cm=26 (sets of rig between first and last)

26+2=28

Answer b: 28

A) ans : 33cm

198/33=6

6x4=24

B) ans : 24

7x3=21 (3 overlapped rings)

21+9(non overlapped ring at the top)=30

b) 198-9=189

189 divided by 7 = 27

27 +1 =28

ans:

a) 30cm

b) 28 rings

(A)

Inner circle=9-1-1=7

Distance=7x4+1+1=30

Ans(A)=30cm

(B)

198-8-8=182

182/7=26

Rings=26+2=28

Ans(B)=28 rings

M2

198-2=196

196/7=28

(a): 9-1=8

8➕8➕8➕9=33

(b): 198➗33=6

6x4=24

(a) Ans:33cm

(b) Ans:24

9+8+8+8=33

b) 198/33=6 (groups of 4)

6x4=24 (total amount of rings)

Ans :34cm

(B)=198-22=176

176/8=22

Ans:22 rings

B) 198/33=6

6x4=24

Ans:a)33cm

B)24

Ans:32cm

(b) 198/8=24cm

Ans: 24cm

36cm-1cm-1cm-1cm=33cm

198/33=6

6x4=24

Ans(a): 33cm

Ans(b): 24

9x4=36

1x3=3

36-3=33

ANS A):33

B) 33/4=8.25

198/8.25=24

Ans B):24

(b) 198cm/ 33 = 6

6 x 4 =24

30x3.14=94.2

94.2x2=188.4

30x3.14/4=23.55

23.55x2=47.1

188.4-47.1=141.3

A) ans : 141.3

2x15x15x3.14=1,413

15x15x3.14/4=176.625

1413-176.625x2=1,059.75

B) ans : 1059.75

Q12

(23.55x2)

A) 1/4 x 2 x 3.14 x 15 = 23.55

23.55 x 2 = 47.1

Ans a: 47.1cm

B) 3.14 x 15 x 15 = 706.5

706.5 x 2 = 1,413

15 x 15 = 225

706.5 / 4 = 176.625

225 - 176.625 = 48.375

225 - (48.375 x 2) = 128.25

1413 - 128.25 = 1,284.75

Ans b: 1284.75cm2

b) 1284.75cm2

2 side: 11.775x2=23.55

b) area triangle. 1/2x7.5x7.5=28.125

area of quarter circle. :

1/4x3.14x7.5x7.5=44.15625

half lezf : 44.15625-28.125=16.031325

full leaf: 16.03125x2=32.0625

area of 1 circle: 3.14x7.5x7.5=176.625

2 circle : 176.625x2=353.25

353.25-32.0625=321.1875

radius:15

1/4x3.14x30=23.55

(b)ans:23.55cm

12(a)

1/2x15x15=112.5

3.14x1/4x15x15=176.625

64.125x2=128.25

3.14x15x15=706.5

706.5x2=1,413

1413-128.25-128.25=1,156.5

(a)ans:1156.5cm2

23.55x2=47.1

Ans(a)47.1cm

3.14x15x15=706.5

1/4x3.14x15x15=176.625

15x15=225

225-176.625=48.375

176.625-48.375=128.25

706.5x2=1,413

1413-128.25=1,284.75

(B)ans:1284.75cm2

(A)

Square=15x15=225

225/2=112.5

1/4x3.14x15x15=176.625

Half leaf =176.625-112.5=64.125

Full leaf=64.125x2=128.25

Ans(a)=128.25

(B)

Circle=3.14x15x15=706.5

706.5x2=1,413

1413-128.25=1,284.75

Ans(B)=1284.75

$72/1=72

72/3=24

24x$0.50=$12

$108-$72-$12=$24

$24/$0.20=120

120+72+24=216

Ans:216

By Danica

wrong but I tried yay

72/3=24

24x0.5=12

108-72-12=24

240/0.20=120

120+72+24=216

Ans : 216

Q12 why I got wrong: I did not minus the leaf again what I found was the total area

I felt that Javier’s method was quite good as it was short and effective.

B) I should minus 9 before dividing and add1 to get the answer.

I think I got the question wrong because I could not visualise what the diagram was showing. I should have minus the thickness of the ring then measured the length.

Question 12:

I think I got the question wrong beacuse I thought that you only had to minus the unshaded part once.

Mdm Kelly said that it was a square inside but I could not solve that question even with

That hint from Mdm Kelly because I lacked

SPATIAL VISUALISATION. I could not see

how to solve the question.

finding out the square instead of the triangle because I used the used 1/2 of the 1/4 circle which is 1/8 and I did not add it back so I got the question wrong

(A)

I did not visualise how and where the square was, so I minused wrongly. I should have outlined where the square was located clearly.

(B)

I only minus the half leaf twice instead of four times.

i should use different methods like model drawing and ratio

I could not solve this question as I felt confused by the overlapping rings. It is also kind of a pattern question which I always find hard to do. I hope to remember this question and understand why we use this method.

Q12. PSLE 2020 Paper 2

I could not solve part b of this question as I had added the area of the two circles but did not subtract the shaded part because I forgot that the circles were overlapped. The method that Mdm Kelly(you) showed us felt a little more efficient and I hope to learn from my mistake.

9x4=36

36-3=33

Instead of taking 9+7+7+7=30

I did not read the question carefully and as a result I did not manage to find the correct answer I also did not know what method to use.

: q5 psle 2020 p2 (blocks) 1.

: q12 psle 2020 p2 (circles) ‘ 2.

why I got it wrong ?

1. i did not understand the question . after the teacher had gone through the work, it became clearer. i used the wrong method to solve the question .

2. i could not visualise the circles . i also made a careless mistake

conclusion?

I need to be more careful in my work. I also need to re read the question. I also need to work out a second method to check my work .

I felt that Alden did the question well and even did a check.

-I did not use ratio unlike most of the people who got it correct and did not properly use grouping

I could not do PSLE paper question 12

-I did not get part B correct because of carelessness