# Graphs: formulas and variables

In this lesson, students use algebra and linear equations to model two real-world scenarios to find information to make the best choice. Students set the aim of saving for a mobile phone (or similar goal) and use linear equations to model the pay rates of two part-time jobs to help make the better decision. This lesson can be taught in tandem with Patterns, rules and graphs, though both can be taught in isolation.

Year level(s) Year 7, Year 8
Audience Teacher
Purpose Teaching resource
Format Web page
Teaching strategies and pedagogical approaches Mathematics investigation, Questioning, Classroom talks, Explicit teaching
Keywords Maths Hub lesson plan

## Curriculum alignment

Curriculum connections Critical and creative thinking
Strand and focus Number, Algebra
Topics Mathematical modelling, Algebraic expressions
AC: Mathematics (V9.0) content descriptions
AC9M7A06
Manipulate formulas involving several variables using digital tools, and describe the effect of systematic variation in the values of the variables

AC9M7N09
Use mathematical modelling to solve practical problems involving rational numbers and percentages, including financial contexts; formulate problems, choosing representations and efficient calculation strategies, using digital tools as appropriate; interpret and communicate solutions in terms of the situation, justifying choices made about the representation

AC9M8A02
Graph linear relations on the Cartesian plane using digital tools where appropriate; solve linear equations and one-variable inequalities using graphical and algebraic techniques; verify solutions by substitution

Numeracy progression Number patterns and algebraic thinking (P6)
Interpreting fractions (P8)
Multiplicative strategies (P9)
Proportional thinking (P2)
Understanding money (P7, P8)