ChalkHour

Year 8 Maths: Percentage change lesson pack

A complete, ready-to-teach KS3 lesson on percentage change. Below is a real sample of what ChalkHour makes: the full pack adds three levels of worksheet, model answers, a teaching explainer and print-ready PDF and Word files.

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Real sample

Percentage Change: Increase and Decrease

This lesson covers the calculation of percentage change, a fundamental skill in Year 8 proportional reasoning. Students will learn to express a change as a fraction of the original amount and convert this to a percentage. The lesson moves from simple integer changes to more complex financial contexts involving profit and loss.

Learning objectives

  • Calculate the percentage increase or decrease of a value using a formula.
  • Identify the 'original' value in a variety of real-life contexts.
  • Solve multi-step problems involving profit, loss, and successive percentage changes.

Lesson plan (60 minutes)

  1. Introduction · 10 min

    Starter: Retrieval practice on simplifying fractions and converting fractions to percentages.

  2. Instruction · 15 min

    Teacher Explanation: Introducing the formula (Change / Original) x 100 with live modelling.

  3. Guided Practice · 10 min

    Guided Practice: Students complete three 'We Do' examples on mini-whiteboards.

  4. Independent Practice · 20 min

    Independent Practice: Differentiated worksheets (Support, Core, Stretch).

  5. Review · 5 min

    Plenary: Multiple-choice quiz to check for understanding and address misconceptions.

Key vocabulary

Original Value
The starting value before any change has occurred.
Change (Difference)
The difference between the new value and the original value.
Percentage Increase
A change that results in a higher value than the original.
Percentage Decrease
A change that results in a lower value than the original.
Profit
The amount of money gained in a transaction (Selling Price - Cost Price).

Core worksheet (first questions)

  1. 1. A gym membership increases from £20 to £23 per month. Calculate the percentage increase.
  2. 2. The weight of a box increases from 250g to 280g. Calculate the percentage increase.
  3. 3. A runner completes a lap in 50 seconds. After training, they do it in 42 seconds. Calculate the percentage decrease in time.
  4. 4. A vintage car bought for £40,000 is now worth £47,000. Calculate the percentage increase.

Quiz (sample)

  1. 1. A toy originally costs £20 but is increased to £25. What is the percentage increase?

    • A. 20%
    • B. 25%
    • C. 80%
    • D. 5%

  2. 2. A bag of flour weighs 500g. After some is used, it weighs 450g. What is the percentage decrease?

    • A. 10%
    • B. 90%
    • C. 11.1%
    • D. 1%

  3. 3. When calculating percentage change, what should the denominator of your fraction be?

    • A. The new value
    • B. The change in value
    • C. The original value
    • D. The larger value

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Support and Stretch worksheets, every answer and model answer, the teaching explainer and common misconceptions, editable and ready to print as PDF or Word.

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