3-7 Fractions and Decimals Course 2 Warm Up Warm Up Problem of the Day Problem of the Day Lesson Presentation Lesson Presentation

3-7 Fractions and Decimals

Course 2

Warm UpWarm Up

Problem of the DayProblem of the Day

Lesson PresentationLesson Presentation

Warm UpDivide.

1. 63 ÷ 9

2. 27 ÷ 3

3. 102 ÷ 3

4. 225 ÷ 25

7

9

34

Course 2


9

Problem of the Day

What three numbers between 0 and 10 can be multiplied together to make a product that matches their sum.1, 2, and 3

Course 2


Learn to identify rational numbers and place them on a number line.

Course 2


Vocabulary

rational number

Insert Lesson Title Here

Course 2


Course 2


You can show –5 and 15 on a number line marked off by 5’s.

–10 –5 0 5 10 15 20

You can show –3 and 4 on a number line marked off by 1’s.

Course 2


A number line can have as much detail as you want. The number line below shows that you can write numbers in many different ways.

–1.25–1.250

–1.00–1.000

–0.75–0.750

–0.50–0.500

–0.25–0.250

0.250.250

0 0

0.500.500

0.750.750

1.001.000

1.251.250

54–

4 4–

2 2–

–1

3 4–

2 4–

1 2–

1 4– 0

4

0 2

0

1 4

2 4

1 2

3 4

4 4

2 2

1

5 4

Graph each number on a number line.

Additional Example 1: Graphing Numbers on a Number Line

Course 2


A. 2 12

–5 –4–3–2–1 0 1 2 3 4 5

2 is between 2 and 3.12

B. –1.4

1 2 3 4 5 –5–4–3 –2–1 0

–1.4 is between –1 and –2.

2 12

–1.4

Try This: Example 1


Course 2



A. 14

1 2 3 4 5 –5 –4–3–2–1 0

is between 0 and 1.14

B. –2.5

1 2 3 4 5 –5 –4–3–2–1 0

–2.5 is between –2 and –3.

14

–2.5

Course 2


The numbers shown on the number lines in Example 1 are called rational numbers. Rational numbers are numbers that can be written as fractions, with integers for numerators and denominators. Integers and certain decimals are rational numbers because they can be written as fractions.

15 = 151 –5 = – 15

1 0.75 =34 –1.25 = – 5

4

Course 2


The top number in a fraction is called the numerator. The bottom is called the denominator. So in the fraction , the numerator is 1 and the denominator is 2.

Remember!

12

Show that each number is a rational number by writing it as a fraction.

Additional Example 2: Writing Rational Numbers as Fractions

Course 2


A. –1.25

–1.25 = – 54

B. 0.75

0.75 = 34

C. –1.00–1.00 = 1

1–

Try This: Example 2


Course 2


Show that each number is a rational number by writing it as a fraction.

A. –1.50

–1.50 = – 32

B. 0.875

0.875 = 78

C. –4.00–4.00 = – 4

4

Additional Example 3: Earth Science Application

Course 2


High tide in Astoria, Oregon, on July 1 was 11:31 A.M. The graph shows how much earlier or later in minutes that high tide occurred in nearby towns.

High Tide Time Corrections

–2

–10

1

2

34

56

Gar

ibal

diSt

. Hel

ens

Char

lest

onVan

couve

rPo

rtla

nd

Corrections to Astoria OR times

Additional Example 3A: Earth Science Application

Course 2


A. Use a decimal to estimate how much later in minutes high tide occurred in Vancouver.


–2

–10

1

2

34

56

Gar

ibal

diSt

. Hel

ens

Char

lest

onVan

couve

rPo

rtla

nd


5.75 minutes later

The bar is about three-fourths of the way between 5 and 6

Course 2


B. Use a fraction to estimate how much earlier in minutes high tide occurred in Charleston.


–2

–10

1

2

34

56


1 minutes earlier

The bar is about one-fourth of the way between –1 and –2.

14

Gar

ibal

diSt

. Hel

ens

Char

lest

onVan

couve

rPor

tlan

d

Additional Example 3B: Earth Science Application

Course 2


C. Use a fraction and a decimal to estimate the difference between the value for St. Helens and the value for Charleston represented on the graph.


–2

–10

1

2

34

56


Gar

ibal

diSt

. Hel

ens

Char

lest

onVan

couve

rPor

tlan

d

3 –(–1 ) = 4 12

14

34

Additional Example 3C: Earth Science Application

The value for St. Helens is about 3 , or 3.5, and the value for Charleston is about –1 , or –1.25.

12

14

Try This: Example 3A


Course 2


Monthly Snowfall (Above and Below Average)

Dec Jan Feb Mar

0

1

3

4

–1–2

–3

A. Use a decimal toestimate how muchbelow average thesnowfall was in January.

2

5

–4–5

0.5 inches below average

The bar is about midway between 0 and 1. In

ch

es

Try This: Example 3B


1.5 inches above average

The bar is about a one and midway between 1 and 2.

Course 2


B. Use a fraction to estimate how much more snow fell in March than the average.


Dec Jan Feb Mar

0

1

3

4

–1–2

–3

2

5

–4–5

Inch

es

Try This: Example 3C


Course 2


1 2

January was 0.5 inches below average and February was 3 inches below average.

C. Use a fraction or a decimal to estimate how much less snow fell in January and February than the average.

+ (–3) = –3 1 2–


Dec Jan Feb Mar

0

1

3

4

–1–2

–3

2

5

–4–5

Inch

es

Lesson Quiz



Course 2


1. –2, 1 , –3 , 12

34

12

Show that each number is a rational number by writing it as a fraction

2. 0.5

3. 1

4. 0.25

125414

14

–4 –3 –2–1 0 1 2 3 4

34–3 –2 1

2121

Documents

3-7 Fractions and Decimals Course 2 Warm Up Warm Up Problem of the Day Problem of the Day Lesson Presentation Lesson Presentation