# Division of Fractions: Balancing Conceptual and Procedural Knowledge Part 2 - PowerPoint PPT Presentation

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Division of Fractions: Balancing Conceptual and Procedural Knowledge Part 2. January 15, 2013 Common Core Leadership in Mathematics2 (CCLM).

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Division of Fractions: Balancing Conceptual and Procedural Knowledge Part 2

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### Division of Fractions: Balancing Conceptual and Procedural Knowledge Part 2

January 15, 2013

Common Core Leadership in Mathematics2 (CCLM)

This material was developed for use by participants in the Common Core Leadership in Mathematics (CCLM^2) project through the University of Wisconsin-Milwaukee. Use by school district personnel to support learning of its teachers and staff is permitted provided appropriate acknowledgement of its source. Use by others is prohibited except by prior written permission.

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

### Learning Intentions and Success Criteria

We are learning to …

• apply and extend understandings of division to fractions that includes a focus on unit fractions in the context of real-world problems.

We will be successful when we can…

• explain and provide examples of standard 5.NF.7 using visual models, contexts, and concept-based language to divide unit fractions by whole numbers and whole numbers divided by unit fractions.

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

Extending Meaning of Division to Fractions

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

CCLM

### Components of Complete Understanding of Division

Division

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

CCLM

### ESTIMATE

Estimate

• Greater than 5?

• Equal to 5?

• Less than 5?

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

### Revisiting Division of Fractions

• Review to Popcorn Problems for last class

• What were the big ideas from these problems?

• What representations did we use?

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

### Juice Party

Quantity: 1/2 gallon of juice

How can I divide that equally among:

• 2 friends

• 5 friends

• Individually solve each problem using reasoning and models

• As a group, take turns and share your reasoning

• Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

Looking at the Standards

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

CCLM

### Standard 5NF 7c

Apply and extend previous understandings of division to divide unit fractions by whole numbers and whole numbers by unit fractions.1

c. Solve real world problems involving division of unit fractions by non-zero whole numbers and division of whole numbers by unit fractions, e.g., by using visual fraction models and equations to represent the problem. For example, how much chocolate will each person get if 3 people share 1/2 lb of chocolate equally? How many 1/3-cup servings are in 2 cups of raisins?

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

### Interpretations of Division

Group Size Unknown

Number of Groups Unknown

I know the total number of objects. I know the number of objects in each group/share. How many equal groups/shares can be made?

Example: How many 1/3-cup servings are in 2 cups of raisins?

* Quotative division, measurement division, grouping, subtractive model.

I know the total number of objects. I know the number of groups/shares. How many objects are in each group/share?

Example, How much chocolate will each person get if 3 people share 1/2 lb of chocolate equally

*Partitive division, sharing model, dealing out.

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

CCLM

### Standard 5NF 7a and 5NF 7b

Apply and extend previous understandings of division to divide unit fractions by whole numbers and whole numbers by unit fractions.1

• Interpret division of a unit fraction by a non-zero whole number, and compute such quotients. For example, create a story context for (1/3) ÷ 4, and use a visual fraction model to show the quotient. Use the relationship between multiplication and division to explain that (1/3) ÷ 4 = 1/12 because (1/12) × 4 = 1/3.

b. Interpret division of a whole number by a unit fraction, and compute such quotients. For example, create a story context for 4 ÷ (1/5), and use a visual fraction model to show the quotient. Use the relationship between multiplication and division to explain that 4 ÷ (1/5) = 20 because 20 × (1/5) = 4.

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

CCLM

### A Tricky Popcorn Party

Serving Size: 3/4 cup of popcorn

How many servings can be made from:

2 ¼ cups of popcorn

5 cups of popcorn

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

CCLM

In pairs, solve each problem using reasoning and models (don’t forget the tape diagram).

• How many ¾ cups servings of popcorn are in 4 ¼ cups of popcorn?

• A serving is ½ of a cookie. How many servings can I make from 3/8 of a cookie?

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

### Learning Intentions and Success Criteria

We are learning to …

• apply and extend understandings of division to fractions that includes a focus on unit fractions in the context of real-world problems.

We will be successful when we can…

• explain and provide examples of standard 5.NF.7 using visual models, contexts, and concept-based language to divide unit fractions by whole numbers and whole numbers divided by unit fractions.

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

CCLM

### Computational Procedures

What procedure do you use to divide fractions?

Write an example of it on your slate.

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

CCLM

### Two Procedures for Division of Fractions

The common denominator method

Invert and Multiply

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

CCLM

### The Common Denominator Method

Have you ever used this?

Does it always work?

Make up division problems to decide when you can use this algorithm.

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

CCLM

### Two Procedures for Division of Fractions

The common denominator method

Invert and Multiply

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

CCLM

### Invert and Multiply Method

• Have you ever used this?

WHY does it work?

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

CCLM

### Why can we “invert and multiply”?

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

CCLM

### Sample student work

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

CCLM

### Examine 6.NS.1

Interpret and compute quotients of fractions, and solve word problems involving division of fractions by fractions, e.g., by using visual fraction models and equations to represent the problem. For example, create a story context for (2/3) ÷ (3/4) and use a visual fraction model to show the quotient; use the relationship between multiplication and division to explain that (2/3) ÷ (3/4) = 8/9 because 3/4 of 8/9 is 2/3. (In general, (a/b) ÷ (c/d) = ad/bc.) How much chocolate will each person get if 3 people share 1/2 lb of chocolate equally? How many 3/4-cup servings are in 2/3 of a cup of yogurt? How wide is a rectangular strip of land with length 3/4 mi and area 1/2 square mi?

• Reread this standard. Do the examples and tasks make more sense to you now?

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year

### Learning Intentions and Success Criteria

We are learning to …

• apply and extend understandings of division to fractions that includes a focus on unit fractions in the context of real-world problems.

We will be successful when we can…

• explain and provide examples of standard 6.NS.1 using visual models, contexts, and concept-based language to divide unit fractions by whole numbers and whole numbers divided by unit fractions.

Common Core Leadership in Mathematics Project, University of Wisconsin-Milwaukee, 2012-2013 School Year