Math6_Q1_W1_D1_Addition_subtraction of fractions.ppt Uploading 0.17Mb of 0.17Mb

2. 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.

3. We need a common
denominator to add
these fractions.

4. 7, 14, 21, 28, 35…
2, 4, 6, 8, 10, 12, 14, 16, 18, 20
We need a common
denominator to add
these fractions.

5. 7, 14, 21, 28, 35…
2, 4, 6, 8, 10, 12, 14, 16, 18, 20
The first number IN COMMON
that appears on both lists
becomes the common denominator

6. x 2
x 2
X 7
x 7 7
6
7 + 6 = 13
13

7. 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

8. x 7
x 7
X 5
x 5 15
7
15 + 7 = 22
22

9. 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

10. x 7
x 7
x 8
x 8 32
21
32 + 21 = 53
53

11. 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

12. X 3
x 5
x 5
x 3
9
10
9 + 10 = 19
19

13. 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…

14. x 11
x 11
X 3
x 3 15
22
15 + 22 = 37
37

15. We need a common
denominator to add
these fractions.
3, 6, 9, 12, 15, 18, 21, 24, 27
6, 12, 18, 24,…

16. x 1
x 1
X 2
x 2 4
1
4 + 1 = 5
5

17. 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

18. x 11
x 11
X 6
x 6 18
11
29
18 + 11 = 29

19. We need a common
denominator to add
these fractions.

20. 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

21. 9, 18, 27, 36, 45, 54, 63, 72, 81
5, 10, 15, 20, 25, 30, 35, 40, 45
The first number IN COMMON
that appears on both lists
becomes the common denominator

22. x 5
x 5
x9
x 9
36
35
36 + 35 = 71
71
36 + 35 = 71

23. 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

24. x 3
x 3
x 2
x 2
19
10 + 9 = 19
9
10

25. 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…

26. x 5
x 5
x 11
x 11
4
15 - 11 = 4
15
11

27. We need a common
denominator to
subtract one fraction
from another.
2, 4, 6, 8, 10, 12, 14, 16, 18, 20 …
10, 20, 30…

28. x 1
x 1
x 5
x 5
2
5 – 3 = 2
5
3

29. Try These
A
F
E
B
C
D

30. 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.

31. Try These
A
F
E
B
C
D
17
27
19
20
10
9
41
28
26
21
13
12