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Ask pupils, in pairs, to work through Example 10 on page 17 in the Pupil Book. They should discuss their understanding as they go, and record any questions. Answer the questions. Pupils can now do Exercise 1D from Pupil Book 3.3.
Part 3 •
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Write a question from Exercise 1D in the Pupil Book on the board, for example, FS question 4: ‘Gabrielle put £2500 in a savings account. At the end of one year she was paid interest of 2% and she left this in her account. At the end of a second year she was paid interest of 2.5%. How much did she have at the end of the second year?’ Discuss with pupils how they could write a formula for this problem. Then ask: ‘What if the original amount is changed? What if the interest rate is changed?’ Now ask pupils to write a similar formula, for example, where the same interest rate of 2% is paid on the original deposit for five years. Encourage pupils to see if they can write the formula more efficiently using powers. (This will move pupils towards the idea of compound interest.) As homework, pupils could research the ways in which different types of interest are used. Answers Exercise 1D 1 9.504 kg 2 546 3 £13 024 4 £2613.75 5 86 bpm 6 a 259 b −4% 7 a 1.9152 m (1.92 m) b 28% (27.68%) 8 The multipliers are 1.16, then 1.25. The product of 1.16 and 1.25 is 1.45, which is the multiplier for an increase of 45%. 9 21% 10 56% 11 58% 12 1.4 × 1.4 = 1.96, so the percentage increase is 96%. 13 a no change b no change c 10% reduction Investigation: Up and down A 1.1 × 0.9 = 0.99, a reduction of 1% B a 0.96, a reduction of 4% b 0.91, a reduction of 9% c 0.84, a reduction of 16% C a reduction of N 2 % D a reduction of 0.25%; 1.05 × 095 = 0.9975 = 1 – 0.0025; 0.0025 = 0.25%
Maths Frameworking 3rd edition Teacher Pack 3.3
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