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## Addition and Subtraction of Fractions Part 1

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### Title: CCSS 101: Standards for Math Practices Author: MPS Last modified by: Connie Laughlin Created Date: 8/13/2010 3:58:48 PM Document presentation format – PowerPoint PPT presentation

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Title: Addition and Subtraction of Fractions Part 1

1
Addition and Subtraction of Fractions Part 1
• Class 3
• October 9, 2012

2
Homework Discussion
• Discuss your response to last weeks homework as
a table group.
•

3
• Standards for Mathematical Practice

4
(No Transcript)
5
Math Practices in Action
• Reflect back to last weeks activities for
comparing and ordering.
• Choose two Standards for Mathematical Practice
that were evident in that work. How were they
evident? Be specific.

6
• An Overview of the Fraction Standards

7
Common Core State Standards for Fractions
• As you read the fractions standards,
• Highlight the word Understand.
• Highlight the words visual model(s).
• As a table, discuss the fraction progressions
that you found by examining these standards.

8

9
Learning Intentions
• We are learning to
• Develop operation sense related to addition of
fractions.
• Understand how estimation should be an integral
part of fraction computation development.
• Read and interpret the cluster of CCSS standards
• We will know we are successful when we can
• Justify our thinking when adding and subtracting
fractions using concrete models and estimation
strategies.
• Clearly explain and provide examples for specific
CCSS standards

10
Big Ideas for Addition and Subtraction of
Fractions
• Fraction addition and subtraction concepts build
from and are dependent upon
• Foundational part-to-whole ideas
• Equivalence ideas
• Magnitude ideas
• Procedural fluency and conceptual understanding
work together to deepen student understanding of

11
Launch Building on What We Know
• Use a model to answer this
• question
• There are some candies in a dish.
• 2/5 of the candies are chocolate.
• 3/10 of the candies are peppermint.
• Are there more chocolate or peppermint candies?

12
Using Estimation
• Aunt Sally has a jar that holds one cup of
liquid. Her salad dressing recipe calls for
• 2/3 cup of oil
• 1/8 cup of vinegar
• 1/2 cup of juice
• Is the jar large enough to hold all the oil,
vinegar and juice?

13
•
• Choose a target number from this set that is less
than 1 or more than 1.
• Make a model of that number using your fraction
strips to serve as a reference.
• Using your fraction strips find combinations to
then 4, etc.
• Record your combinations. Also record any
conjectures your group makes as you work on the
• If you feel that you have explored all
combinations for your first target number, pick a
second one and do subtraction.

14
Example of target less than 1
15
• What patterns emerged as you made your
combinations?
•
• as you engaged in these explorations?
• How did the fraction strip model support your
thinking?

16
Connections to Standards 4.NF.3a, 4.NF.3b and
5.NF.1
• 1. Read these standards, highlighting important
words and phrases.
• 4.NF.3 Understand a fraction a/b with a gt 1 as a
sum of fractions 1/b.
• a. Understand addition and subtraction of
fractions as joining and separating parts
referring to the same whole.
• b. Decompose a fraction into a sum of fractions
with the same denominator in more than one way,
recording each decomposition by an equation.
Justify decompositions, e.g., by using a visual
fraction model. Examples 3/8 1/8 1/8 1/8
3/8 1/8 2/8 2 1/8 1 1 1/8 8/8 8/8
1/8.
• 5.NF.1 Add and subtract fractions with unlike
denominators (including mixed numbers) by
replacing given fractions with equivalent
fractions in such a way as to produce an
equivalent sum or difference of fractions with
like denominators. For example, 2/3 5/4 8/12
15/12 23/12. (In general, a/b c/d (ad
bc)/bd.)
• 2. In your group, discuss highlighted key ideas
in this standard and questions you may have about
these standards.
• 3. Work as a group to cite three specific
examples of how the previous activity made sense
of these standards.

17
NF Progression Document
• Study the sections, diagrams, and margin notes on
• Highlight important words and phrases, and note
surprising ideas or questions raised.
• In particular, note how the standards
• In your group, discuss highlighted key ideas and

18
Learning Intentions
• We are learning to
• Develop operation sense related to addition of
fractions.
• Understand how estimation should be an integral
part of fraction computation development.
• Read and interpret the cluster of CCSS standards