unit 4: linear relations lesson 2: scatter plots and relationships name the coordinates of these...

Unit 4: Linear Relations

Lesson 2: Scatter Plots and Relationships

Name the coordinates of these points:

A: ( )B: ( )C: ( )D: ( )

Unit 4: Linear Relations

Lesson 2: Scatter Plots and RelationshipsLearning Goals:

• I can create a scatter plot and analyze it to look for patterns

• I can describe the relationship between two variables

What is a Scatter Plot?

• A scatter plot shows the relationship between two sets of numeric data.

• Scatter plots reveal trends. If a relationship exists between the two sets of data, the scatter plot will show us this relationship.

Unit 4: Linear Relations

Lesson 2: Scatter Plots and Relationships

Success Criteria – How to create a scatter plot:• Collect data and organize it in a table

of ordered pairs.• Plot the coordinates(ordered pairs) on

a graph with labeled axes• Analyze the data by looking for a

pattern• If a pattern exists, describe it

Unit 4: Linear Relations

Lesson 2: Scatter Plots and Relationships

Example:Julie gathered information about her age and height from the markings on the wall in her house.

Unit 4: Linear Relations

Lesson 2: Scatter Plots and Relationships

Age (Years)

Height (cm)

1 70

2 82

3 93

4 98

5 106

6 118

7 127

8 135

We need to plot the data on the graph.

Unit 4: Linear Relations

Lesson 2: Scatter Plots and Relationships

Age (Years)

Height (cm)

1 70

2 82

3 93

4 98

5 106

6 118

7 127

8 135

Does a relationship exist?

Can you describe it?

Unit 4: Linear Relations

Lesson 2: Scatter Plots and Relationships

• If the data we collect is made up of values that can change, we call these values variables.

• Unlike a constant (like the number of seconds in a minute), a variable can change values (like the number of seconds you can hold your breath).

Unit 4: Linear Relations

Lesson 2: Scatter Plots and Relationships

Unit 4: Linear Relations

Lesson 2: Scatter Plots and RelationshipsRaise your hand if you drank a hot beverage (hot chocolate, coffee, tea) within the last month.

If I asked this same questions in August, what do you think the result would be?

Why?

• When the data we have is related in some way, the variable that depends on the other variable is called the Dependent Variable.

• The variable that doesn’t depend on the other is called the Independent Variable.

• When graphing, the independent variable always gets placed along the x-axis, and the dependent on the y-axis.

• In a table of values the independent variable is placed in the left hand column and the dependent variable in the right hand column.

Unit 4: Linear Relations

Lesson 2: Scatter Plots and Relationships

x Y

1 0

2 2

3 4

4 6

5 8

6 10

Unit 4: Linear Relations

Lesson 2: Scatter Plots and Relationships

Independent Variable

Dependent Variable

Unit 4: Linear Relations

Lesson 2: Scatter Plots and Relationships

••

•

•••

•••

Dep

en

de

nt

Independent

Unit 4: Linear Relations

Lesson 2: Scatter Plots and RelationshipsWhat about Julie’s experiment? Which variable was independent, and which was dependent? • Dependent Variable:

• Independent Variable:

ExamplesWhich of these variables are related, and if they are, which is the dependent variable? 1. Cost of a dozen donuts and the year. 2. The number of pet cats adopted from the

Humane Society last year and the number of computers purchased last year.

 3. Your shoe size and your age.

Unit 4: Linear Relations

Lesson 2: Scatter Plots and Relationships

How do we know if a relationship exists between two pieces of data?

• A relationship exists if a change in one variable will cause a change in the other.

• Look for relationships in the following scatterplots:

Unit 4: Linear Relations

Lesson 2: Scatter Plots and Relationships

Unit 4: Linear Relations

Lesson 2: Scatter Plots and Relationships

Th

e a

vera

ge c

ost

of

a D

VD

Unit 4: Linear Relations

Lesson 2: Scatter Plots and Relationships

How far Mrs. Gonzalez-Day Runs

•

•

•

•

••

••

•

Cost of DVDs VS. Running Distance

Unit 4: Linear Relations

Lesson 2: Scatter Plots and Relationships

• When the relationship on a graph follows a straight line, we call it a linear relationship.

Unit 4: Linear Relations

Lesson 2: Scatter Plots and Relationships

Practice

Pg. 63 Q. 1, 2, 5, 6, 7, 8, 11Pg. 107 Q. 1, 2, 3, 4

Unit 4: Linear Relations

Lesson 2: Scatter Plots and Relationships