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Published byHomer Bruce Modified over 5 years ago
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Review Rewrite the sentences 5×7=35 7+7+7+7+7=35 2×9=18 9+9=18
Multiplication =35 Multiplication 2×9=18 9+9=18 Addition 6+6+6=18 3×6=18 4×4=16 Addition =16
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In focus The vertical direction: 3 columns, 4 in each column.
3×4 = = 12 The horizontal direction: 4 rows, 3 in each row. 4×3 = = 12
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Let’s learn 3 columns 4 rows 3×4 =12 4×3 =12 4 in each column 3 in each row 3×4 = 4×3 Exchange the position of two factors, the product is same.
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Exchange
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Describe the situation with addition or multiplication.
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Describe the situation with addition or multiplication.
( ) columns, ( ) in each column. Addition: =16 Multiplication : 8×2= =16
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Describe the situation with addition or multiplication.
( ) rows, ( ) in each row. Addition: 8+8=16 Multiplication : 2×8= 8+8=16
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=16 8×2=16 8+8=16 2×8=16 =8×2=2×8=8+8=16
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Circle and fill in different way : How many stars in the picture?
7×2= =14 2×7=7+7=14 = 7×2= 2×7= 7+7 = 14
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2+2+2+2+2+2+2+2=8×2=2×8=8+8=16 2+2+2+2+2+2+2=7×2=2×7=7+7=14
Which addition is handy? =8×2=2×8=8+8=16 Repeated 7 times Repeated one more time =7×2=2×7=7+7=14 Repeated 6 times Repeated one more time What’s the purpose to learn Exchange? Using Exchange can solve what problem?
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Guided Practice 2+2+2+2+2+2+2+2+2= 3+3+3+3+3+3+3= 4+4+4+4+4+4= = + 9 2
× = + 9 2 18 7 3 21 = = + + × × = 6 4 24 × = = + + + × =
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Write 2 multiplications according to the picture.
3×5=15 2×3=6 5×3=15 3×2=6
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Challge If I give you 12 circles, can you arrange them in 2 different ways and write the exchange sentences. □×□=□×□
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