Lesson 2 - Percentages increase and decrease with multipliers

Objective

To use multipliers to calculate percentage increases and decreases

Resources

Calculators, rulers, IWB, Computers for extension [optional]

Starter

Open the L2 starter presentation but don't progress to the second slide just yet. Ask students to match up one blue, one yellow and one orange tile ... so that they start with a blue tile then find the correct %increase or %decrease yellow tile that takes them to one of the red tiles. You may want to go through one example with them. When they have finished you can go through the answers on the board either by showing them slide 2 or by getting students to come up to the board and drag the tiles to the correct positions.

Alternatively with less able groups, print out the first slide and cut out all parts, then ask students to arrange them in order themselves. Or similarly if you have access to computers, ask students to drag and drop the tiles into the correct positions.

Lesson

Go through the lesson powerpoint which teaches students how to find multipliers to work out percentage increases and decreases quickly in their heads. When you get to the matching tile slide, ask students to make the connections between tiles. By clicking on ‘pen’ you can physically draw the lines on the slide to show which ones have been done.

Activity

The worksheet involves students completing questions in order and joining them up. Each straight line that joins the questions to its answer passes through a letter, students need to write the letter down to break the code. Make it clear that students are not to ‘tell’ each other the answers and the important thing here is the mathematics.

For more able students who finish these quickly give them the extension [this can be done on a computer or printed out as a worksheet]. By typing the correct answer, the answer box should turn green. The point of this extension is to allow students to realise that, for example, a 10% increase followed by a 5% increase is not the same as a 15% increase. Ask students to write down in words why this is not the case.

Answers to the first worksheet should be straight forward and students should realise themselves if they have done it correctly. Look at the extension with the whole class and discuss what some people may have discovered. Encourage those who didn’t get onto the extension to try for themselves some of the questions.

Plenary

For the plenary run the powerpoint slideshow. Students can take turns in playing this memory game. You can have teams or pupils playing individually. If students have access to computers they can play this themselves but make sure they do not save their finished slideshow over the original.

Download the lesson 2 plan in Word format

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