Bargain Packs

Questions 1a and 1b call for multiplication and division respectively. You could encourage the students to do all these equations in their heads and then invite them to say what particular strategies they used to do the mental calculations. If a few students need to jot down some figures to aid their memories, that is fine,
but they could explain what they jotted down and why.
Question 2 introduces the level 5 Number objective of working with ratios. At this level, the questions may be more easily understood in terms of simplifying fractions. To simplify fractions, the students need to understand the identity principle, that is, if you divide a number by 1, the number retains its identity. In other words, the number stays the same, although its name may change. For example, question 2a can be worked out as follows:

Dividing by 2/2 is the same as dividing by 1. Note that 1 itself can have many names, including many fractional names. Similarly, question 2c can be figured out as follows:

This translates to four coloured pencils for the price of three.
Take the time to help your students to understand the identity principle because it is a powerful idea that is used in mathematics at higher levels. At this level, it is what enables equivalent fractions to be generated. For example:

The relevant aspect here is the understanding that a number retains its identity if it is multiplied by 1. So 3/4 is the same fractional number as 9/12 or 75/100, although obviously its name is different.

Answers to Activity

1. a. i. $1.20
ii. $3.60
iii. $3.60
iv. $3.00
v. $20
b. i. 24 cents each
ii. 90 cents each
iii. 60 cents each
iv. $1.00 per kg
v. $4 a pair
2. a. 3 pairs for the price of 2
b. 4 L for the price of 3 L or 2 L for the price of 1.5 L
c. 4 coloured pencils for the price of 3
d. 5 g for the price of 3 g