Interest Rates Explained

Overview

In this fourth lesson of Mastering Money Matters, students investigate how interest rates affect savings and loans. They use simple calculations to compare outcomes over time, interpret the financial impact of different rates, and begin evaluating how interest influences personal financial decisions.

Learning intentions

• Students will explain what an interest rate is.
• Students will calculate simple interest on savings and loans.
• Students will compare how interest accumulates over time.
• Students will identify benefits, costs and risks associated with interest rates.

Success criteria

• I can define interest rate, principal, interest earned and interest charged.
• I can use a percentage to calculate simple interest.
• I can explain why a saver benefits from interest while a borrower pays interest.
• I can use calculations to justify a sensible financial choice.

Curriculum links

• The role of Australia’s financial sector and its effect on economic decision-making by individuals and businesses.
• Interpret information and data to explain economic cause-and-effect relationships and predict financial impacts.
• Develop and evaluate a response to a financial issue using cost-benefit analysis or relevant criteria.
• Create explanations and arguments using economic and business concepts and research-informed evidence.

Lesson structure (60 minutes)

1. 0–7 min · Hook and prior knowledge. Open with the opening question and savings-versus-loan visual and ask: “Would you rather receive $50 interest or pay $50 interest?” Students make an initial choice, explain their reasoning to a partner, and complete a quick show of hands. Clarify that today’s lesson focuses on why the same concept can be helpful for savers but costly for borrowers.

2. 7–17 min · Direct teaching: key concepts. Use the key vocabulary and worked examples to explain principal, interest, interest rate, savings, loans, lender and borrower. Model the simple-interest formula: interest = principal × rate × time, with the rate written as a decimal. Work through $1,000 saved at 5% for one year: $1,000 × 0.05 × 1 = $50, giving a total of $1,050. Students record the definitions and identify who pays and who receives interest in each example.

3. 17–29 min · Guided calculation. Display the guided calculation sequence and complete the first example together: $600 borrowed at 8% for one year. Students calculate the interest, total repayment and explain why the borrower repays more than the amount borrowed. Pairs then solve two examples on the interest-rate calculation worksheet: $800 saved at 4% for two years and $1,500 borrowed at 6% for two years. Pause after each question to check percentage-to-decimal conversion, units and totals.

4. 29–43 min · Compare financial choices. Direct students to the comparison table on the interest-rate calculation worksheet. In pairs, students compare three options: saving $1,200 at 3% for three years; borrowing $1,200 at 7% for three years; and borrowing $1,200 at 7% for one year. They calculate the interest and final amount for each, then annotate which option creates an income, a cost or a financial risk. Ask pairs to discuss how the length of time and rate change the outcome.

5. 43–53 min · Decision and justification. Show the decision prompt and criteria: “A student wants $1,000 for a new laptop. They can save $100 per month or borrow $1,000 at 9% for two years. Which information should they consider before deciding?” Students use the worksheet calculations and write a short recommendation. Require reference to at least two criteria, such as total cost, ability to repay, time, savings buffer and financial risk. Invite two or three students to share; address the misconception that a low monthly repayment always means a low total cost.

6. 53–60 min · Review and exit ticket. Use the recap and exit-ticket instructions to revisit the formula and ask students to explain the difference between interest earned and interest charged. Students complete the final questions on the interest-rate calculation worksheet independently: “Calculate the interest on $2,000 saved at 4% for two years” and “In one sentence, explain one reason a borrower should compare interest rates.” Collect responses to identify students requiring further support in the next lesson.

Resources

• the Interest Rates Explained slide deck
• the interest-rate calculation worksheet
• Projector or interactive display
• Calculators or calculator function on approved devices
• Whiteboard and markers
• Highlighters or coloured pencils
• Student exercise books

Assessment

• Listen to partner explanations and question students during the hook and direct teaching to check understanding of who pays and receives interest.
• Check guided and paired calculations for correct decimal conversion, formula use, units and final totals; provide immediate feedback.
• Use the independent exit ticket to assess calculation accuracy and students’ ability to explain a financial impact or risk.

Differentiation

• Provide a formula card, a worked example with colour-coded steps, a percentage-to-decimal reminder and a calculator for students needing support.
• Pair students strategically and provide sentence starters: “The borrower pays interest because…” and “The better option is… because…”.
• For EAL learners, pre-teach the terms principal, rate, loan, savings, lender and borrower using the visuals in the slides; allow verbal rehearsal before writing.
• Extend capable students by asking them to compare two rates over different time periods and explain why a savings buffer and ability to repay should influence a borrowing decision.