Activity Card for Unit 3

Handout 1

Modeling and Analyzing Household Water Usage Data

In this activity your group will explore the class’ water usage data in CODAP to model and analyze the relationship between people and amount of water usage. CODAP is the modeling tool your group will use to describe trends in bivariate data visualizations to tell the story of the relationship between people and water usage. This is part of the Modeling and Analyzing phase of the data science process.

Start with a discussion on the data visualization of the amount of people and gallons of water used. Open the graph of the whole class data so that all of your group members can see on one computer. Use the following questions to facilitate the group’s conversation:

• What does the data look like? What do you notice?
• According to the data visualization, does there appear to be a relationship between people and the amount of water used in a household?
• When two variables are related to each other, this is called a ‘correlation’. Do you think the number of people and the amount of water used are correlated? Why or why not?

Next, on your group’s computer, create a line that you think best represents your data applying the ‘Movable Line’ feature in CODAP. Note: only one person can move the line at a time. This will be your estimated line of best fit.

Your goal, with your group, is to estimate what this line of best fit might be by moving your line.

• What line best represents the trend of your data? Move the line discussing why one location might be better than another location.
• What can you change about your line? How might that change affect your predictions?
• If a household uses 1,000 gallons per month, how many people might live there?

• In order to adjust the axis in CODAP, you will need to click the axis and drag it.

• Given your line, what would you predict for households of 15 people? Does this seem like a reasonable estimate for a household of this size? What assumptions change as the household size changes?
• When you adjust your estimated line, how do your predicted values change? By how much?
• What story does this line tell you about water usage across households? Make a statement describing this relationship.

Be prepared to share with the class:

A description of the relationship between the number of people in a household and amount of water used. Create a copy of  your estimated line of best fit. Write a description of how you chose where to place this line in your maths journal and what story it tells you about the data. What were your considerations? Why do you think your line is a good representation of the data? Include also your group’s prediction for a household of 15 people.