Lesson 10
Using Probability to Determine Whether Events Are Independent
Lesson Narrative
The mathematical purpose of this lesson is to find and use probabilities to recognize dependent and independent events. The work of this lesson connects to previous work because students used twoway tables to investigate independence. The work of this lesson connects to upcoming work because students will determine independence of events and calculate conditional probabilities using data collected in class. The Math Talk activity gives students a reason to use language precisely (MP6) and gives the opportunity to hear how they use terminology and talk about characteristics of the items in comparison to one another.
Technology isn't required for this lesson, but there are opportunities for students to choose to use appropriate technology to solve problems. We recommend making technology available.
Learning Goals
Teacher Facing
 Use probabilities to justify (using words or other representations) that events are dependent or independent.
 Use results from data collected in class to estimate probabilities.
Student Facing
 Let’s take a closer look at dependent and independent events.
Learning Targets
Student Facing
 I can collect data and use it to estimate probabilities.
 I can use probabilities to decide if events are independent.
CCSS Standards
Addressing
Glossary Entries

conditional probability
The probability that one event occurs under the condition that another event occurs.

dependent events
Dependent events are two events from the same experiment for which the probability of one event depends on whether the other event happens.

independent events
Independent events are two events from the same experiment for which the probability of one event is not affected by whether the other event occurs or not.