Changing the Subject of a Formula — Interactive Lesson (Ages 14–16)

Do your students freeze when a formula needs rearranging? This 34-slide interactive lesson teaches changing the subject of a formula, using inverse operations to work from the outside in.

Mastering Changing the Subject of a Formula at GCSE

Students start with what the subject of a formula is, the letter that appears on its own on the left-hand side, and why changing it is useful. They then learn to peel a formula apart like the layers of an onion, applying inverse operations to undo what has been done, and finish with real-world formulae, such as a phone plan of £5 a month plus 5p a minute, and F = P ÷ 240 for electrical fuse ratings.

What’s Included

• 34-slide interactive lesson on changing the subject of a formula
• Learning objectives on the purpose and process of rearranging formulae
• Inverse operations explained with an onion-layers idea
• Real-world examples including a phone plan and fuse ratings
• Sixteen quiz questions plus fill-in-the-blank, sorting and drag activities

Key Benefits for Students

• Makes rearranging a clear, step-by-step process
• Connects formulae to real situations
• Builds fluency with inverse operations
• Instant feedback on answer questions

Why Teachers Love It

• No prep — unzip the download and open index.html to start
• Ready for whole-class teaching on an interactive whiteboard
• Self-marking questions support independent practice
• Suits teaching, revision and homework
• A long, structured lesson that can be split across sessions

Love this? You’ll love…

• Factorising Quadratic Expressions ax² + bx + c — Interactive Lesson (Ages 14–16)
• Laws of Indices — Interactive Lesson (GCSE, Ages 14–16)
• Solving Inequalities — Interactive Lesson (GCSE, Ages 14–16)

A dependable addition to a GCSE algebra topic, giving students a clear method they can apply to any formula. Confident rearranging is essential for science, geometry and later A-Level maths.

Build confident algebra skills today — Add to Basket.

FAQ

What year group is this for? Years 10–11 (ages 14–16), GCSE.

How do I open the lesson? Unzip the download and open index.html in a web browser.

Is it self-marking? Yes, with instant feedback on the questions.