Lesson 2

Determining pre-GST Prices

Topic: Number and Algebra - Financial Mathematics

Year Level: 8

ACARA (or NESA) Content description and Syllabus content indicator(s):

Investigate and calculate the Goods and Services Tax (GST), with and without the use of digital technologies

Syllabus Working Mathematically Indicator(s):

› interpret GST information contained on receipts (Communicating)

› explain why the pre-GST price is not equivalent to 10% off the GST-inclusive price (Communicating, Reasoning)

Learning Goals:

interpret GST information on receipts
apply percentage calculations to sample goods to calculate GST when the GST-inclusive price is known
calculate the pre-GST price of an item given the GST-inclusive price

Materials/Resources required:

Description of Lesson:

Orientation [5 mins] - Mini-whiteboard activity to review previous lesson work on what GST is, how to calculate GST. Project questions on the board for students to solve.
Launch [10 mins] - Review any misunderstandings from previous lesson (understanding that the value of the GST itself is not equivalent to 10% of the GST-inclusive price). Teacher teaching time; samples on the board to explain: (i) The GST-inclusive price, is 110% of the pre-GST price. (ii) Pre-GST price is not equivalent to 10% off the GST-inclusive price.
Explore
Summarise [5 mins] - Teacher-led discussion recapping the key learning ideas. Discuss why the pre-GST price is not equivalent to 10% off the GST-inclusive price. What would this look like? (Use some examples from students' tables). (AFL)

Homework/Follow up Tasks:

Textbook: Ex 6.6 'GST' (pp. 168-170)
Students calculate how much it would cost them to make the recipe if the items were bought at the pre-GST value. Students then calculate how much it cost them when the items are GST-inclusive. What is the difference in cost? (Segue for following lessons on spending, discounts and profit/loss)