Unit 5 Direct and indirect proportion Unit focus
This unit focusses on the following: • direct and indirect proportion • solve problems using direct and indirect proportion.
Background information
Learners should already know about the concepts of ratio and rate. They should also know about relationships between two variable quantities that can be represented in various equivalent ways such as in words, by flow diagrams, tables or formulae. Learners should also know how to interpret and draw global graphs and how to use tables or ordered pairs to plot points and draw graphs on the Cartesian plane.
Exercise 1 Guidelines on how to implement this activity
Since direct and indirect proportion is new to the learners it is important to demonstrate various examples on the board. Total payments for the purchase of a number of units (e.g. for tins of cool drink) in relation to the price per unit, offers many examples of direct proportion. Let the learners do Exercise 1 in the class and discuss the answers with them once they have finished the exercise.
Suggested answers 1 2 3 4 5 6
Exercise 2 Guidelines on how to implement this activity
Work through an example of a graph of a direct proportion such as the example in the Learner’s Book. The verbal description of a direct proportion as worded in the Learner’s Book is very important. So analyse and discuss it with the learners and link it to the equation y = cx and the straight line graph. Demonstrate the Worked examples to the learners. Stress the characteristic of an indirect proportion as a relationship of the form xy = constant. Let the learners do Exercise 2 in the class and discuss the answers with them once they have finished this exercise.
Yes, the table shows direct proportion as y = 3x
No, the table does not show direct proportion as the rate is not constant. Yes, the table shows direct proportion as y = x Yes, the table shows direction proportion as y = 5x
__ 2
No, the table does not show direct proportion as the rate is not constant. Yes, the table shows direct proportion as y = − x
___ 11
Learner’s Book page 33 Learner’s Book page 32
Learner’s Book page 31
Chapter 1: Numbers and integers
41
CHAPTER 1
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71
