Intent

In this activity, students continue to use rugs as a visual model for probability.

Mathematics

This activity reemphasizes that the distinct outcomes of a probabilistic situation must add to 1. It also incorporates a review of fractions, decimals, and percentages into further work with an area model.

Progression

Have students do this activity individually, likely for homework, following or together with Portraits of Probabilities.

Approximate Time

20 minutes for activity (at home or in class)

10 minutes for discussion

Classroom Organization

Individuals, followed by whole-class discussion

Doing the Activity

Little or no introductory discussion of the activity is necessary.

Discussing and Debriefing the Activity

Allow volunteers to share the situations they created for Questions 1 and 2, and ask the class to evaluate whether the situations fit the information. Help students find the missing probabilities ( 712712 size 12{ { {7} over {12} } } {} and .35, respectively) by asking, What is the area of your other region? What does that tell you about the probability of the other outcome?

Students may recognize that Question 3 presents an impossible situation, as the probabilities total to more than 1. If not, you can try to build on their work in finding the missing probabilities in Questions 1 and 2 to uncover the difficulty. If students find a solution to Question 3 by creating overlapping outcomes, commend them for their creativity.