Lesson: How to Count Lions

Split your class into groups of three or four. Tell students that you want to find out information (age, number of siblings, eye color, etc.) about the students in your school, but you don’t have enough time to survey them all. Ask: How can I make valid generalizations about the entire school population without surveying all students? Have each group brainstorm a plan that would solve your problem. Then allow each group to share their plan. Discuss the pros and cons of each of these plans as a class.

Create a KWLS chart with your class. Ask them what they know and what they want to know about lions. Then play the video twice for students. During the first viewing, tell students to only watch and listen to the video. During the second viewing, students can jot down facts they learned about lions that they did not know before. Then have a class discussion about what new information they learned from the video.

Have students work in pairs to read each section. Ask them to summarize the section’s central idea and to record any definitions that are new to them. Tell them to pay careful attention to the methods used to count lions while reading the “Counting the Ways” section, and to pay careful attention to the pros and cons of SECR while reading the “By a Whisker” section. Then have pairs discuss this closing question: Why is it important to count lion populations? Select a few volunteers to share their responses with the class.

Have a volunteer read the introduction of the “Understanding Sampling Methods” box on page 10 aloud to the class. Then, as you read through each of the sampling methods, provide the following examples and ask students to give thoughts or provide their own.

• For convenience, say: I want data on the whole school. I’m going to collect data from this math class here because I have you all with me, and it’s easy to collect the data.

• For voluntary, say: I want data on the whole school. I’m going to pass out an optional survey to every student in the school. I’ll count the data that I collect from the students who decided to hand the survey in.

• For simple random, say: I want data on the whole school. I’m going to put each student’s name on a piece of paper. I’m going to put each piece of paper in a box and randomly pull out 50 names.

• For cluster random, say: I want data on the whole school. Each student in the school takes one math class. I’ll randomly choose different math classes and collect data from the students in those classes.

• For stratified random, say: I want data on the whole school. I’m going to break the school up into groups by grade. I’m then going to select 30 students randomly from each grade.

• For systematic random, say: I want data on the whole school. I’m going to alphabetically assign each student in the school a number. I will collect data from every student with a number that’s a multiple of 5.

Tell students that you want to find out the average number of cell phones each household in your town or city has. Have students reread the descriptions of different sampling methods on page 10. For each of the sampling methods, have students write down a plan for collecting the data you want.