Percentages - Percentage of an amount (range of percent) - Presentation

In a comprehensive set of teaching slides, students are guided through the process of calculating varying percentages of amounts, with a particular emphasis on multiples of 10%. The lesson begins with an interactive discussion where students are encouraged to consider how they might find 20% of a given amount. Subsequent activities involve using a bar model to visualise and calculate percentages such as 20%, 30%, 70%, and 90% of various numbers. For example, to find 40% of 90, students learn to calculate 10% of 90, which is 9, and then multiply this by 4 to get 36. This method is applied to other percentages, reinforcing the concept that finding a percentage involves breaking it down into more manageable parts, such as multiples of 10%.

Further exercises introduce the technique for finding 5% of a number by first dividing by 10 and then by 2, with examples such as 5% of 160 and 5% of 280. This method is compared to the alternative approach of directly dividing by 20. More complex calculations are also explored, such as finding 65% of 30m, 35% of 170g, and 15% of £50. Additionally, reasoning activities challenge students to evaluate different methods for finding 20% of a number, acknowledging that dividing by 5, finding 1% and multiplying by 20, or adding two 10% values are all valid strategies. The lesson encourages students to notice patterns in percentages, such as the commutative property exemplified by the equality of 45% of 60 and 60% of 45. Independent work tasks prompt students to apply these strategies to find percentages of various amounts and critically evaluate the efficiency of different methods.