**This is the students’ version of the page. Log in above for the teachers’ version.**

# A big idea

This applet allows you to generate questions involving exponential growth and decay, and reveal amounts at intermediate time periods, not just at a start and an end point. You can reposition the arrow to show the relationship between amounts at any two time periods.You can click on the label to the right of the arrow to cycle through different information.

# Growth and decay problems (exponential)

**Teachers**: log in to access the following:

- Slides in PPTX (with click-to-reveal answers)
- Slides in PDF (one slide per page, suitable for importing into IWB software)

- Worksheet (with space for student work)
- Handout (slides with exercises only; 4 per page for reduced printing)

- Skills drill worksheet (15 questions on one side of A4; answers included)

- Random Question Generator – compound interest: find final amount
- Random Question Generator – growth and decay problems: find final amount
- Random Question Generator – growth and decay problems: find initial amount
- Random Question Generator – growth and decay problems: find rate of growth/decay
- Random Question Generator – growth and decay problems: find time period
- Random Question Generator – mixed questions

**Teachers**: log in to access these.

#### Unlimited practice questions: compound interest and depreciation

# Simple interest

*Simple* interest (as opposed to *compound* interest, covered above) is rarely seen in the real world, but can make appearances in maths textbooks and exams.

#### Unlimited practice questions: simple interest

**Teachers**: log in to access the following:

- Random Question Generator – simple interest: find final amount
- Random Question Generator – simple interest: find rate of interest
- Random Question Generator – simple interest: find time period
- Random Question Generator – mixed questions

# Comparing simple and compound interest

This applet allows you to compare how an initial amount of £100 would grow over a period of up to 15 years at a given percentage rate using simple interest and compound interest. You can drag the slider underneath the horizontal axis to show year-by-year growth.

With thanks to Yip Wing Chung, Felix, whose Simple interest Compound interest worksheet is available here. Material modified and embedded here under the CC-BY-SA 3.0 license.**Teachers**: log in to view this content.