Lesson 6: Observational Studies

Objective:

Students will learn that an observational study is a data collection method in which subjects are observed and outcomes are recorded. They will learn how to collect this type of data and make informal inferences about the results.

Materials:

Stick Figures Cutouts (LMR_1.2_Stick Figures) from Unit 1, Lesson 2

Note: Advanced preparation required (see step 1 below).
Turning Observations into Data handout (LMR_3.2_Observations_to_Data)

Vocabulary:

observational study

Essential Concepts:

Observational studies are those for which there is no intervention applied by researchers.

Lesson:

From Unit 1, Lesson 2, redistribute one full set of 8 cards from the Stick Figures handout (LMR_1.2) to each student team.

Advanced preparation required: Print the Stick Figures handout (LMR_1.2). The handout can then be cut into the 8 cards. You will need enough sets of the cards for each student team to share a full set. For example, if there are 5 student teams in a class, then 5 copies of the file will need to be printed so that each team gets all 8 cards.
Have students recall that they used these cards in Unit 1, Lesson 2. When they used them in Lesson 2, the data was collected, recorded, and organized, but without particular structure to it.

LMR_1.2
Then, distribute one copy per student of the Turning Observations into Data handout (LMR_3.2).

LMR_3.2
Every student from the team will then select one of the cards from the team’s pile of 8, and should begin working through the Turning Observations into Data handout individually.
As the students finish each part of the handout, they should compare their responses with their student teams.
Go over the names of the variables in Part 1 by doing a quick Whip Around by teams. Then, select a couple of teams to share the information on the first row and one of the columns.
Part 3 of the handout asks the students to consider the following research question:

What determines the number of friends a person has on social media?
Once the students have completed the handout, discuss the variable that they thought was best associated with the number of friends on social media. They should have seen that a person’s GPA was related to the number of friends. More specifically, the higher a person’s GPA, the more friends he/she had.
Ask a few students to share out their responses to the very last question: “Can you think of another variable (not necessarily given in the pictures) that might impact both the number of friends AND the variable you selected? Give an example and explain how it might impact each of the variables.” Answers will vary, but one example could be: a person’s self-esteem level (if he/she is confident in school, his/her grades might be higher; higher confidence could also be a reason for a person having more friends).
Remind students that in the previous section, they learned about the elements of an experiment. In teams, ask students to discuss how collecting this data is similar or different from experiments. Then have a whole class discussion about this comparison, guiding students to realize that there were no assignments to groups and no treatment was applied. The subjects (i.e. the people displayed on the cards) were simply observed, and then information about them was recorded.
Inform students that an observational study is a data collection method in which subjects are observed and outcomes are recorded. No treatment is applied to the subjects. Instead, researchers are simply watching something happen and have absolutely no control over it.
In lesson 7, students will learn more about the differences between experiments and observational studies and what conclusions they can make about each.

Class Scribes:

One team of students will give a brief talk to discuss what they think the 3 most important topics of the day were.