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 Relationships Learning 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)

We need to plot the data on the graph. Unit 4: Linear Relations Lesson 2: Scatter Plots and Relationships Age (Years) Height (cm)

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 Relationships Raise 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

xY Unit 4: Linear Relations Lesson 2: Scatter Plots and Relationships Independent Variable Dependent Variable

Unit 4: Linear Relations Lesson 2: Scatter Plots and Relationships Dependent Independent

Unit 4: Linear Relations Lesson 2: Scatter Plots and Relationships What about Julie’s experiment? Which variable was independent, and which was dependent? Dependent Variable: Independent Variable:

Examples Which 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

The average cost of a DVD 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, 11  Pg. 107 Q. 1, 2, 3, 4 Unit 4: Linear Relations Lesson 2: Scatter Plots and Relationships