Adding & Subtracting Fractions Teacher Notes: Use this presentation to teach the steps for adding and subtracting fractions with unlike denominators.
Mar 26, 2015
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Adding & Subtracting Fractions Teacher Notes:
• Use this presentation to teach the steps for adding and subtracting fractions with unlike denominators.
• It is assumed that students have a thorough understanding of the process for making equivalent fractions.
• CLICK HERE to view a demonstration with opportunities for students to practice making equivalent fractions.
We need a common denominator to add
these fractions.
7, 14, 21, 28, 35…
2, 4, 6, 8, 10, 12, 14, 16, 18, 20
We need a common denominator to add
these fractions.
7, 14, 21, 28, 35…
2, 4, 6, 8, 10, 12, 14, 16, 18, 20
The first number IN COMMONthat appears on both lists
becomes the common denominator
x 2
x 2
X 7
x 7 7
6
7 + 6 = 13
13
We need a common denominator to add
these fractions.
5, 10, 15, 20, 25, 30, 35, 40, 45
7, 14, 21, 28, 35, 42, 49, 56, 63
x 7
x 7
X 5
x 5 15
7
15 + 7 = 22
22
We need a common denominator to add
these fractions.
7, 14, 21, 28, 35, 42, 49, 56, 63
8, 16, 24, 32, 40, 48, 56, 64, 72
x 7
x 7
x 8
x 8 32
2132 + 21 = 53
53
We need a common denominator to add
these fractions.
3, 6, 9, 12, 15, 18, 21, 24, 27
5, 10, 15, 20, 25, 30, 35, 40, 45
X 3
x 5
x 5
x 3 9
10
9 + 10 = 19
19
We need a common denominator to add
these fractions.
3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33
11, 22, 33, 44, 55, 66, 77…
x 11
x 11
X 3
x 3 15
2215 + 22 = 37
37
We need a common denominator to add
these fractions.
3, 6, 9, 12, 15, 18, 21, 24, 27
6, 12, 18, 24,…
x 1
x 1
X 2
x 2 4
1
4 + 1 = 5 5
We need a common denominator to add
these fractions.
11, 22, 33, 44, 55, 66, 77…
6, 12, 18, 24, 30, 36, 42, 48, 54, 60, 66, 72
x 11
x 11
X 6
x 6 18
11
29
18 + 11 = 29
We need a common denominator to add
these fractions.
We need a common denominator to add
these fractions.
9, 18, 27, 36, 45, 54, 63, 72, 81
5, 10, 15, 20, 25, 30, 35, 40, 45
9, 18, 27, 36, 45, 54, 63, 72, 81
5, 10, 15, 20, 25, 30, 35, 40, 45
The first number IN COMMONthat appears on both lists
becomes the common denominator
x 5
x 5
x9
x 936
3536 + 35 = 71
71
36 + 35 = 71
We need a common denominator to add
these fractions.
12, 24, 36, 48, 60, 72, 84, 96
8, 16, 24, 32, 40, 48, 56, 64, 72, 79, 80, 88, 96
x 3
x 3
x 2
x 2
19
10 + 9 = 19
9
10
5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55
We need a common denominator to
subtract a fraction from another.
11, 22, 33, 44, 55, 66, 77…
x 5
x 5
x 11
x 11
4
15 - 11 = 4
15
11
We need a common denominator to
subtract one fractionfrom another.
2, 4, 6, 8, 10, 12, 14, 16, 18, 20 …
10, 20, 30…
x 1
x 1
x 5
x 5
2
5 – 3 = 2
5
3
Try These
A
F
EB
C
D
Answers On Next Slide
• Each click on the next slide reveals an answer.
• Check your papers.
• If you discover an incorrect answer, be able to explain your mistake.
Try These
A
F
EB
C
D1727
1920
109
4128
2621
1312
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