Lesson 3 - Repeated percentage changes

Objective

To calculate repeated percentage changes using multipliers

Resources

Scientific calculators, IWB, computers for extension [optional]

Starter

Open up the starter activity on the board.  Students have to put blue tiles in order so the value and percentage increases make sense. Then they should do the same for the orange, red and the yellow tiles. When they have finished, some students could be asked to step forward and move them on the board [remember not to run the slide show if you want to do this]. Pay particular close attention to the blue and yellow tiles as the same percentage increase/decrease has altered the values by different amounts. Ask students to explain why. Explain to the class that quite often we need to repeatedly increase or decrease values by a certain percentage and today we are going to do it using multipliers.

Lesson

Open the lesson presentation and go through the slides. Describe the advantages of using multipliers over taking each increase/decrease separately. Show students how to complete the number search by going through the examples.

Activity

Give students a number search and ask them to complete it. Ensure they do not strike through the numbers as they will find it difficult to find other numbers in the search. Finding their number in the number search can be a verification that they have calculated [and rounded] their answers correctly. For students who complete this activity quickly, give them the extension activity, you may need to explain that they can solve this by trial and error changing the power of the multiplier each time. Some more able students may not need to have this explained to them.

Plenary

Show students the plenary presentation and ask them to try and work out the answers using a calculator. Discuss how it might have been done without a calculator for more able students.

Download the lesson 3 plan in Word format

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