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: ( )


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.



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



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



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.



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?



• 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).




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.



x Y

1 0

2 2

3 4

4 6

5 8

6 10



Independent Variable

Dependent Variable



••

•

•••

•••

Dep

en

de

nt

Independent


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.



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:



Th

e a

vera

ge c

ost

of

a D

VD



How far Mrs. Gonzalez-Day Runs

•

•

•

•

••

••

•

Cost of DVDs VS. Running Distance

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



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 name the coordinates of these...

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