Page 41 - 新思维数学教师用书5 试读样张

1 The number sysTem

Description: Show a place value chart. Tell the learners that it is like the one they used in Stage 4 but it has been
extended to include decimal numbers.

100 200 300 400 500 600 700 800 900
10 20 30 40 50 60 70 80 90
1 2 3 4 5 6 7 8 9
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09

Ask learners to describe the grid. 1 1
100s 10s 1s 10 s 100 s
Answer: 100 to 900 going across. Divide by 10 each time
you move down a row. 6 5 1

Point to 0.4 and ask: Ask:
• How do you say this number? • How do you say this number?
• What is ten times this number?
Answer: six point five one.
Answers: zero point four, 4.
• How do you decompose this number?
Point to 0.04 and ask, ‘How do you say this number?’
Answer: 6 + 0.5 + 0.01
Answer: zero point zero four.
• Can you regroup this number in a different way?
Repeat for other decimals, emphasising the language.
Show a partly labelled place value grid and ask, ‘What are Answer: 5 + 1.5 + 0.01, other answers are possible.
the titles of the columns marked with a question mark?’
• How do you write the number equivalent to
Answer: tenths, hundredths. 6 ones + 5 tenths + 1 hundredth? Remind learners
that when they combine numbers in this way, they
are composing a number.
100s 10s 1s ? ?
Answer: 6.51

Repeat for other numbers and also ask questions about
specific place values:
• What is the value of the digit 4 in the number 6.48?
Place numbers (up to 2 decimal places) on the grid and 4
ask learners to say the numbers. Then reverse the process: Answer: 4 tenths or 10
say numbers (up to 2 d.p.) and ask learners to place the
numbers on the grid. • What is the value of the digit 6 in the number 4.06?
Shade cells in the displayed chart to make numbers with
two decimal places, for example shade 6, 0.5 and 0.01 to Answer: 6 hundredths or 6
make 6.51. 100

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4+ ྍනົඔ࿐࢝ഽႨ඀ ᆞ໓č1 Ď ཮@නૼ JOEE