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Primary National Strategy. Mathematics 3 plus 2 day course: Session 2. Objectives. To identify ways in which a number line can be used to teach division, including representing the quotient as a fraction To consider approaches to mental and written division calculations
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PrimaryNational Strategy Mathematics3 plus 2 day course:Session 2
Objectives • To identify ways in which a number line can be used to teach division, including representing the quotient as a fraction • To consider approaches to mental and written division calculations • To review progression in division in Years 4, 5 and 6
Number lines and grouping Slide 2.2
TASK What division calculation is represented if: • the step size is 4? • the right-hand marker represents 18? • the middle marker represents 6? Slide 2.3
17 ÷ 5 = 3 2 5 Remainders Slide 2.4
Remainders 17 ÷ 5 = 3 2 5 Slide 2.5
Discussion point 1 Does this calculation have different answers in different contexts? 22 ÷ 4 When should a remainder be expressed as a whole number? When should the quotient be expressed as a fraction or decimal?
Answer: 258 Informal recording of 43 × 6 Slide 2.7
240 + 18 = 258 Answer: 258 Informal recording of 43 6 Slide 2.8
Answer: 12 Informal recording of 84 ÷ 7 Slide 2.9
10 + 2 = 12 Answer: 12 Informal recording of 84 ÷ 7 Slide 2.10
Answer: 918 Progression from the grid method ... 27 × 34Approximate answer: 30 × 30 = 900 Slide 2.11
Answer: 918 ... to an efficient standard method 27 34Approximate answer: 30 30 = 900 Slide 2.12
Progression from ‘chunking’ ... 560 ÷ 24Approximate answer:550 ÷ 25 = 22 Answer: 23 r 8 Slide 2.13
... to efficient ‘chunking’ ... 560 ÷ 24Approximate answer:550 ÷ 25 = 22 Answer: 23 r 8 Slide 2.14
... to an efficient standard method 560 ÷ 24Approximate answer:550 ÷ 25 = 22 Answer: 23 r 8 Slide 2.15
Summary • The language ‘divided by’ and images of repeated subtraction or division on a number line help to secure pupils’ understanding of division in KS1 and the early years of KS2 • It is essential that these early ideas are taught well and that pupils develop a conceptual and visual framework linked to the language of division
Summary • The middle years of KS2 should focus on: • how to use both factorising and partitioning as mental strategies for division • how to record these strategies to support or explain their thinking • how and when to express a quotient with a remainder, or as a fraction or decimal (a model of a number line is helpful here)
Summary • The later years of Key Stage 2 should focus on making informal written methods for division, such as ‘chunking’, as efficient as possible, as in the long division method • Pupils working confidently at level 4 should also be able to carry out ‘short’ division of a three- or four-digit number by a single-digit number