Year level: 6

Strand: Number

Lesson length: 2 x 60 mins

In this lesson, we use the context of grocery shopping to engage students in calculating percentage discounts and the discovering real cost of items offered through different pricing discounts and offers.

### Achievement standard

By the end of Year 6, students solve problems involving finding a fraction, decimal or percentage of a quantity and use estimation to find approximate solutions to problems involving rational numbers and percentages.

### Content descriptions

Students solve problems that require finding a familiar fraction, decimal or percentage of a quantity, including percentage discounts, choosing efficient calculation strategies and using digital tools where appropriate. AC9M6N07

Students approximate numerical solutions to problems involving rational numbers and percentages, including financial contexts, using appropriate estimation strategies. AC9M6N08

### General capabilities

Numeracy

Critical and Creative Thinking

• Analysing (Interpret concepts and problems Inquiring)
• Inquiring (Identify, Process and Evaluate information)
• Review student work samples from the challenge tasks to assess their proficiency with converting decimals and percentages, use of the operations to calculate percentage and the use of varied strategies to find the cost of items.
• Use slide 15 to check student calculations for challenge tasks.
• Represent the same number as a percentage, decimal and fraction.
• Use place value to describe decimal numbers.
• Identify familiar common fractions, such as 1 2 ,   1 3 ,   3 4 ,   1 10 .
• Explain that per cent means ‘out of one hundred’; it shows an amount out of 100, so 10 per cent is 10 out of 100.
• Use the symbol % to represent a percentage.
• Use percentage to describe the size of a change in a number or measurement; this change is referred to as a percentage increase or decrease (when shopping, the decrease is called a discount).
• Add, subtract, multiply and divide fractions and decimals.

Terminology

Discount, sale, percentage, buy one get one free

Some students may:

• confuse whole-number language and decimal fraction language, for example, tens (10) and tenths (0.1)
• not recognise that finding a percentage is finding one part out of a whole, for example, 32 per cent is 32 parts out of 100
• have difficulties converting a decimal percentage, as they consider it a decimal rather than a percentage, and do not see the need to do so.