Fraction CuisenRod

TEACHING AND LEARNING OF FRACTIONS USING CUISENAIRE ROD

• Introducing Fractions

• Comparing Fractions

• Equivalent Fractions

• Addition/Subtraction of Fractions

INTRODUCING FRACTIONS

? ?

1 Orange = 2 _____?______

1 Oren = 2 Yellow

1 Yellow = ? rod Oren

21

1 Yellow = Orange

If one Orange = 1, one rod Yellow = .

21

21 Numerator

Denominator

Find all pairs of rods in which one

rod is half the length of the other

rod.

21

What does each pair indicate?

Each pair indicates .

21

How big is

21 ?

Fraction is a relationship and not a fixed quantity!

1 Dark Green = 3 ………..?

? ? ?

1 Dark Green = 3 Red

1 Red = ? Dark Green

1 Red = Dark Green

If one Dark Green = 1, one Red = .

31

31

Find two pairs of rods that have the same relationship as the pair of rods indicated above.

31

How many pairs of rods can you

obtain for ? 41

41

How many pairs of rods to

represent ? 51

51

Try to show:

101 ,

91 ,

81 ,

71 ,

61

1019181

61

71

Can you show:

108 ,

54 ,

63 ,

87 ,

94 ,

72

?

72

94

87

108

63

54

Write the fraction for each pair of rods;

1. 2.

3. 4.

5.

COMPARING FRACTIONS

Numerator is “1”

Numerator is non-1

one of the denominators is a factor of the other

denominators are non-factor

NUMERATOR IS “1”

Show and by

using these Dark Green.

21

31

Take out 2 Dark Green.

21

31

Which fraction has the bigger value?

Show and by

using Chocolate rods.

41 ,

21

81

21

41

81

21

41

81

Which fraction has the biggest value?

Smallest value?

21

41

81

81

41

21

Reminder:Comparison between fractions can only be done if we refer to the same unit (the whole).

81 ,

41 ,

21

To compare the three fractions above, the three fractions must be represented by using the same coloured rod as the unit, that is Chocolate(8cm).

21

41

81

81

41

21

Which fraction is bigger?

Can show or proof by using the appropriate rods?

91 ,

31

31

91

31

91

Without using CRods, indicate which fraction is bigger.

Check or verify your answer by using CRods.

101 ,

51

What conclusion or generalisation can you make when comparing the value of fractions whose numerators are “1”?

More than Less than

21

31

31

91

51

101

>

>

>

DENOMINATORS NON-1

Try to compare:

85 dan

43


Reminder: we can only compare the value of fractions if they have the same

denominator!

DENOMINATORS NON-1

Try comparing:

85 and

43

Not the same

DENOMINATORS NON-1

Try comparing: 85 and

43

Not the same

85

43

43

85

85

43

Show the two fractions by using the appropriate rods.

Compare:


65 dan 3

2

32

65

65

32

DENOMINATORS ARE NON-FACTORS

Try comparing:


43 dan

32

Which rod is appropriate to be used as 1 unit?

43 dan

32

We need to find the least common multiple (LCM) for both denominators (that is 3 and 4) by using CRods.

Take out the appropriate rod that represents “3” and “4”. Put them side by side with the same

starting point. Which rod is shorter? Add another same coloured rod. Continue until both

rows of rods are of the same length.

The total length of either row is the Lowest Common Multiple for 3 and 4.

43 and

32

LCM for 3 and 4 = 12

43 and

32

Use rods for 12 as one unit.

Show and . 32

43

=12

43

32

32

43

43

32

32

43

or

Same length

? 53 and

32

Using the same approach, can you compare

53 and

32

LCM = 15

32

53

Challenge: can you compare the values of three fractions?

a. Using Cuisenaire Rods

b. Finding LCM

EQUIVALENT FRACTIONS

Name the fraction represented by the pair of CRods above

Use Red to represent each rod.

21

21

42

Use Whites to represent Reds.

42

21

21

42

84

84

42

21 EQUIVALENT

FRACTIONS

Write down two equivalent fractions for the pair of rods below:

93

31


64

32


106

53

93

31

84

42

21

106

53

What is the relationship between the numerator and denominator of each equivalent fraction?

64

32

6

32

96 2

86

4

2 61

Complete:

Need skills on Addition of Whole Numbers using CRods

ADDITION/SUBTRACTION OF FRACTIONS

** Peringatan: ingat operasi tambah dengan

nombor bulat?

** Kita telah menggunakan analogi

“sambungkan” menjadi gerabak!

** Jadi kemahiran ini akan dipindahkan ke

operasi dengan pecahan!

ADDITION/SUBTRACTION OF FRACTIONS

Example:

** How do we avoid this misconception?

ADDITION OF FRACTIONS

Ingat: pecahan adalah satu hubungan. Di sini apakah hubungan putih dengan hijau mudah? Satu per tiga. Apakah hubungan putih dengan hijau mudah

yang sama? Satu per tiga. “Whole” yang sama, maka jumlahnya adalah dua

pertiga!


Proceed with the same “whole” . (Penyebut yang sama)

Have more practices.


A. One denominator is a factor of the other denominator.

83

21

Example:

83

21

The bigger denominator is 8.

Represent both fractions by using Chocolate.

Can both fractions be represented by Chocolate)?

21

83

83

21

84

83

84

87

103

52

Try

104

52

103

103

52

107

103

104

B. Denominators are different and are not multiples

Bigger denominator is 3.

Which Rod will be appropriate to be used as the “whole” for both fractions?

Can both fractions be represented by the Dark Green?

31

21 Contoh:

31

21

LCM for 2 & 3 = 6

21

31

61

62

63

63

62

41

32

Try:

125

123

128

41

32

= 12

C. Adding and Subtraction of 3 fractions

Try to explain the following using CRods?

41

32

21

41

32

21

(i) Find LCM for 2, 3 & 4

41

32

21

(ii) Representing the above fractions using appropriate CRods.

32

21

41

41

32

21

(iii) Writing the equivalent fractions

128

32

126

21

123

41

(iii) Finding the answer

1211

123

128

126

41

32

21

Try to explain the following?

43

61

32

(i) Find LCM for 3, 6 & 4

43

61

32

(ii) Representing the above fractions.

43

61

32

(iii) Write the equivalent fractions and calculate the answer.

411

1231

1215

129

122

128

43

61

32

Terima Kasih

Thank You

Fraction CuisenRod

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