## Lesson 2.2 – Relationships between Two Quantitative Variables

• Distinguish between explanatory and response variables for quantitative data.
• Make a scatterplot to display the relationship between two quantitative variables.
• Describe the direction, form, and strength of a relationship displayed in a scatterplot, and identify outliers.

We are using the Barbie Bungee data to learn about explanatory and response variables, scatterplots and how to describe a distribution.  Students used the applet to enter the data in to TWO QUANTITATIVE VARIABLES.  The activity begins by asking students to identify what type of variables they are using.  It’s important that students can accurately identify which menu to choose when using the applet so they can do their homework on their own.

Application 2.2: More sugar, more calories?

Students used the applet to make a scatterplot for the calorie content and sugar content of various candy bars. One common misconception students had was that they wanted to enter the type of candy bar (i.e.Butterfinger) into the applet instead of the variables, sugar and calories.

Notes

We used the common AP Stats acronym, DOFS (Direction, Outliers, Form and Strength).  Though DOFS may sound nonsensical, the students found it really helpful.

Bonus: If you have time, try the online only Lesson 2.2A: Timeplots.