41

• Modeling Fractions

Power Up facts jump start Power Up 41

Count up by 25s from 0 to 200.

Count up by fourths from 0 to 2.

It’s morning. Draw hands on your clock to show 8:59.

Write the time in digital form. 8:59 a.m.

The afternoon temperature was 16°C. At night it was

9 degrees cooler. Mark your thermometer to show the temperature at night. 7°C

mental math a. Estimation: Round $175 to the nearest hundred dollars.

$200

b. Number Sense: 18 − 8

10

c. Time: A decade is 10 years. How many years are in

2 decades? 20 years

d. Money: Find the value of these bills and coins:

problem solving $3.53

Ted wrote this sequence to help him find the number of feet in 1 yard, 2 yards, 3 yards, and so on. Which number is incorrect in his sequence? Why? 17; sample: The pattern is

“count up by 3,” and 3 more than 15 is 18.

3, 6, 9, 12, 15, 17, 21, 24, 27

Lesson 41

223

New Concept

We have used fractions to describe parts of an hour and parts of a dollar.

Thirty minutes is 1 of an hour.

2

A quarter is 1 of a dollar.

4

We have also used models to illustrate fractions.

In this lesson we will make fraction manipulatives. First, we will learn some vocabulary.

• The denominator of a fraction shows how many equal parts make the whole.

• The numerator shows how many parts we are describing. Activity

Fraction Manipulatives

Materials: Lesson Activities 15 and 16, crayons or colored pencils, scissors, paper envelope or locking plastic bag

1. Your teacher will give you four fraction circles on two sheets of paper.

2. Use crayons or colored pencils to color each circle a different color. Use only one color for a circle. Color both the front and back of the circle.

224

Saxon Math Intermediate 3

3. After you color all the circles, cut out each one. Then cut each circle into pieces by cutting on the lines.

4. You will use your fraction manipulatives for the examples and for later lessons and problem sets.

5. Store your fraction manipulatives in an envelope or plastic bag when you are not using them.

Example 1

Name the fraction of a circle shown using digits and words.

We see that the circle is divided into 4 equal parts. One of the parts is shaded.

We find the fraction piece that is one of four equal parts. The fraction is 1, which

4

we read “one fourth.”

What is the denominator of the fraction? What does

Analyze

it tell you?

4; sample: Four of these parts make a whole circle.

Example 2

Name the fraction shown.

We see that the circle is divided into

5 equal parts. Three of the parts are shaded. The fraction shown is 3, which

5

we read “three fifths.”

Analyze

tell you?

Lesson Practice

What is the numerator of the fraction? What does it

3; sample: There are 3 of the 5 pieces shown.

a. What is the denominator of the fraction 4?

5

b. What is the numerator of the fraction 2?

3

5

2

Use your fraction manipulatives to model each fraction shown below. Then name the fraction using digits and words.

c.

d.

1

;

2

one half

e.

2

;

3

two thirds

2

;

5

two fifths

Lesson 41

225

Written Practice

Distributed and Integrated

1. Rosa’s ticket cost $4.75. Her brother’s ticket cost $3.25. What was the total price of the two tickets? $8.00

(18, 22)

2. Bradley read 32 pages before dinner. He read some more pages after dinner. Bradley read 58 pages in all. How many pages did he read after dinner? Write a number sentence, and then answer the question. 32 + = 58; 26 pages

(36)

3. There were 238 fans at the game. Write that number using words.

(12)

two hundred thirty-eight

4. Round the number of fans in problem 3 to the nearest hundred.

(15)

200

5. This map shows John’s house, Mike’s house, and school. Today

Mike is stopping at John’s house before going to school. If Mike does not retrace his steps or return to his house, what route will