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3.2 Selection and computations

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1. The following activity is for your portfolio.

Look carefully at the assessment table before you begin – your teacher will allocate a code from 1 - 4 for the different sections.

Challenge!

1.1 Carry out a survey in your class and find out how many learners read which magazines. Write you information down in a table, e.g.

Magazine You Time SA Runner Fair Lady
Number of learners ................. ................ ................. .................

1.2 Now show the information by means of a pie diagram.

1.3 Answer the following questions:

a) Which magazine is the most popular?

b) Which magazine is read the least?

c) Which magazine is YOUR favourite?

Why?

BRAIN–TEASER!

Who am I?

a) If you subtract me from 1 2 size 12{ { { size 8{1} } over { size 8{2} } } } {} , you will get 3 8 size 12{ { { size 8{3} } over { size 8{8} } } } {}

b) If you cut me into sixths, you will have 24 6 size 12{ { { size 8{"24"} } over { size 8{6} } } } {}

c) If you double me, you will get 4 1 2 size 12{ { { size 8{1} } over { size 8{2} } } } {}

  1. If you halve me, you will get 2 1 12 size 12{2 { { size 8{1} } over { size 8{"12"} } } } {}
  2. If you calculate 3 4 size 12{ { { size 8{3} } over { size 8{4} } } } {} of me, you will get 12

Activity 5:

To solve problems in context [lo 1.6.1]

Split up into groups of three. You will be given the necessary paper to work on. Remember to discuss the solutions amongst yourselves beforehand and then you can do them neatly on paper.

1. Mrs Mvusi buys 7 metres of material. If she wants to make each one of her four children a bright cushion for his or her room, how many metres of material can she use for each one? (All the cushions are of the same size.) Give each answer as a fraction.

2. Mr Muruvan buys 9 pieces of dry sausage that he wants to share equally among himself, his wife and their five children. What fraction of the sausage will each one get?

3. Grandpa Ben would like to divide R30 equally among his four grandchildren. What is the amount each one will get?

a) Did she divide it fairly?

b) What fraction does each person get?

c) Write your answer as an improper fraction:

1.3 Sketch the solutions to the following:

a) Divide eight fizzers equally between five children.

b) Divide five milk tarts equally between 12 guests.

1.4 Calculate the following:

a) Divide R5,00 equally between four children.

b) Divide 13 pies equally between eight learners.

Activity 6:

To use a series of techniques to do calculations [lo 1.10.5]

1. It is important for us to know how to key in ordinary fractions on a pocket calculator. This will help us find the answers to problems in no time.

Did you know?

If you want to show a fraction on the calculator, e.g. 5 7 size 12{ { { size 8{5} } over { size 8{7} } } } {} you must key in 5 ÷ 7 = .

1.1 How does the calculator show the following fractions? Write down what you key in.

a) 3 5 size 12{ { { size 8{3} } over { size 8{5} } } } {} ______________

b) 6 7 size 12{ { { size 8{6} } over { size 8{7} } } } {} ______________

c) 5 8 size 12{ { { size 8{5} } over { size 8{8} } } } {} ______________

d) 1 12 size 12{ { { size 8{1} } over { size 8{"12"} } } } {} ______________

e) 3 4 size 12{ { { size 8{3} } over { size 8{4} } } } {}

BRAIN–TEASER!

There are seven cows in a camp. Isolate them by means of three fences so that each cow is in its own small camp.

Indicate with a coloured pencil crayon where you would put the fences.

Assessment

Learning outcomes(LOs)
LO 1
Numbers, Operations and RelationshipsThe learner is able to recognise, describe and represent numbers and their relationships, and counts, estimates, calculates and checks with competence and confidence in solving problems.
Assessment standards(ASs)
We know this when the learner:
1.1 counts forwards and backwards fractions;
1.2 describes and illustrates various ways of writing numbers in different cultures (including local) throughout history;
1.3 recognises and represents the following numbers in order to describe and compare them:
  • common fractions to at least twelfths;
1.5 recognises and uses equivalent forms of the numbers listed above, including:
1.5.1 common fractions with denominators that are multiples of each other;
1.6 solves problems in context including contexts that may be used to build awareness of other Learning Areas, as well as human rights, social, economic and environmental issues such as:
  • financial (including buying and selling, profit and loss, and simple budgets);
LO 5
Data handlingThe learner will be able to collect, summarise, display and critically analyse data in order to draw conclusions and make predictions, and to interpret and determine chance variation.
We know this when the learner:
5.3 organises and records data using tallies and tables;

Memorandum

ACTIVITY 1

1. 1.1 1 8 size 12{ { { size 8{1} } over { size 8{8} } } } {} 1.2 3 12 size 12{ { { size 8{3} } over { size 8{"12"} } } } {} = 1 4 size 12{ { { size 8{1} } over { size 8{4} } } } {}

1.3 3 12 size 12{ { { size 8{3} } over { size 8{"12"} } } } {} = 1 4 size 12{ { { size 8{1} } over { size 8{4} } } } {} 1.4 6 10 size 12{ { { size 8{6} } over { size 8{"10"} } } } {} = 3 5 size 12{ { { size 8{3} } over { size 8{5} } } } {}

1.5 1 5 10 size 12{1 { { size 8{5} } over { size 8{"10"} } } } {} = 1 1 2 size 12{1 { { size 8{1} } over { size 8{2} } } } {} 1.6 1 3 8 size 12{1 { { size 8{3} } over { size 8{8} } } } {}

ACTIVITY 2

1. It is the same

2. 10 ; 5

7.1: 21

7.2; 20

  • :300

7.4 :168

ACTIVITY 3

  1. 1.1: 200 ml

1.2: 1 500 m

1.3: 300 g

1.4; 5 6 size 12{ { { size 8{5} } over { size 8{6} } } } {}

1.5: 2 500 mm or 2,5 m or 2 1 2 size 12{ { { size 8{1} } over { size 8{2} } } } {} m

BRAIN-TEASER!

a) 1 8 size 12{ { { size 8{1} } over { size 8{8} } } } {}

  1. 4
  2. 2 1 4 size 12{ { { size 8{1} } over { size 8{4} } } } {}
  3. 4 1 6 size 12{ { { size 8{1} } over { size 8{6} } } } {}
  4. 16

1.4 a) R1,25 / 125c

  1. 1 5 8 size 12{ { { size 8{5} } over { size 8{8} } } } {}

ACTIVITY 7

1.1 a) 3 size 12{ div } {} 5 = 0,6

  1. 6 size 12{ div } {} 7 = 0,8571428
  2. 5 size 12{ div } {} 8 = 0,625
  3. 1 size 12{ div } {} 12 = 0,0833333
  4. 3 size 12{ div } {} 4 = 0,75
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Source:  OpenStax, Mathematics grade 5. OpenStax CNX. Sep 23, 2009 Download for free at http://cnx.org/content/col10994/1.3
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