Experience First

To start this lesson, allow students to come to the whiteboard to make tally marks showing how many children are in their family. Turn these tally marks into probabilities (we suggest fractions) that will be used for the remainder of the activity. 

 

While question #5 is fairly intuitive, you can use it to remind them of some ideas from probability. P(X>=3) = P(X=3 OR X=4 OR X=5 OR X=6+). Because each of these events are mutually exclusive, we can simply add each of the individual probabilities. 

 

When distinguishing between discrete and continuous random variables, we used the following language: Discrete random variables are “countable number of values with gaps” and continuous random variables are “infinite number of values with no gaps”. 

 

In the last question of the activity, students are asked to do a normal distribution calculation, which they learned in Lesson 2.5. Remember to have copies of Table A ready for students and be prepared to do a refresher. Being able to do normal distribution calculations is so important for student’s later success in this class, and now is a great time to review. 

​

Formalize Later

When debriefing question #8 in the activity, remind students of the expectation when doing a normal distribution calculation. Here is what we suggest:

• Drawing of the normal distribution, labeled with the N(mu,sigma) notation

• Mean value labeled on the normal distribution

• Boundary value labeled on the normal distribution

• Correct shading for the area of interest

 

You might want to remind students about how to find the area to the right (using 1 – area from Table A) and the area between two values (subtract the two areas from Table A).

 

Later in Chapter 9, students will need to be able to find the area under a normal distribution in order to calculate a P-value for a significance test.