Impact of changes to GST
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Introduction
In this activity, students investigate the effect it would have on families if the GST rate was increased and the GST base was broadened to include all goods. It provides an opportunity for students to use mathematical modelling to solve practical and real-world problems involving percentages.
Achievement standard
By the end of Year 8, students recognise irrational numbers and terminating or recurring decimals. They apply the exponent laws to calculations with numbers involving positive integer exponents. Students solve problems involving the 4 operations with integers and positive rational numbers. They use mathematical modelling to solve practical problems involving ratios, percentages and rates in measurement and financial contexts. Students apply algebraic properties to rearrange, expand and factorise linear expressions. They graph linear relations and solve linear equations with rational solutions and one-variable inequalities, graphically and algebraically. Students use mathematical modelling to solve problems using linear relations, interpreting and reviewing the model in context. They make and test conjectures involving linear relations using digital tools.
Students use appropriate metric units when solving measurement problems involving the perimeter and area of composite shapes, and volume of right prisms. They use Pythagoras’ theorem to solve measurement problems involving unknown lengths of right-angle triangles. Students use formulas to solve problems involving the area and circumference of circles. They solve problems of duration involving 12- and 24-hour cycles across multiple time zones. Students use 3 dimensions to locate and describe position. They identify conditions for congruency and similarity in shapes and create and test algorithms designed to test for congruency and similarity. Students apply the properties of quadrilaterals to solve problems.
They conduct statistical investigations and explain the implications of obtaining data through sampling. Students analyse and describe the distribution of data. They compare the variation in distributions of random samples of the same and different size from a given population with respect to shape, measures of central tendency and range. Students represent the possible combinations of 2 events with tables and diagrams and determine related probabilities to solve practical problems. They conduct experiments and simulations using digital tools to determine related probabilities of compound events.
Content descriptions
Use mathematical modelling to solve practical problems involving rational numbers and percentages, including financial contexts; formulate problems, choosing efficient calculation strategies and using digital tools where appropriate; interpret and communicate solutions in terms of the situation, reviewing the appropriateness of the model (AC9M8N05).
Teacher resources
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Using spreadsheets
Student learning resources
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What goods and services are GST-free?
How will changes to the GST impact your family?
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Suggested activity sequence
This sequence is intended as a framework to be modified and adapted by teachers to suit the needs of a class group. If you assign this activity to a class, your students will be assigned all student resources on their 'My learning' page. You can also hand-pick the resources students are assigned by selecting individual resources when you add a work item to a class in 'My classes'.
Part A: GST-free goods and services
- Use a grouping strategy to organise students in groups of 3 or 4.
- Groups read the explainer and construct a brief rationale of why some goods and services are GST-free.
- Groups share their reasons. When all reasons have been provided, discuss the concept of GST and develop a simple class rationale of why basic foods are GST-free.
Part B: Reviewing GST calculations
This section may be skipped depending on the readiness of your students, or on whether they completed the Percentages and GST activity.
- Explicitly teach students how to calculate GST from both the GST exclusive price and the GST inclusive price (that is, working forwards and backwards). Calculating GST at 10 percent – How-to-sheet might be a helpful resource for students.
- Display and explain how to use spreadsheets using the visualiser.
Part C: Investigating changes to GST
- As a class, read through the investigation.
- Students complete the investigation. Students may benefit from working individually and/or in small discussion groups. It might be useful for students to have a copy of Making an Excel spreadsheet using GST as an example – How-to-sheet
- As a class, discuss students’ findings.