Most of the lesson today will be spent reading and reviewing the scenario so students are aware there is a criminal at large and how we plan to find him/her. I usually say that the criminal is among us and by the end of the activity, we should be able to make an arrest. You can even get very elaborate with the "game" of finding the suspect by asking a school resource officer to come in and present the case to the class for added effect and interest. You can make the case details different and specific to your school such as saying the criminal broke into a vending machine and took all the cash or something silly like the criminal ran off with all the pencils for state testing. Any introduction that will make the students engage with the activity and want to find out who in the class is the thief.
Partnerships: I usually put students into partnerships for ease of measuring their body parts. I partner girls to girls and guys with guys because they are touching each other's hips and legs so I just play it safe with same gender pairing.
Close the lesson by asking students to record their measurements as a scatter plot for each of the bivariate data: Femur vs. Height, Armspan vs. Height, and Foot Length vs. Height. I use the large graph paper, chart paper that resembles a post-it note. I pre-label each graph with a title, x and y-axis labels and numbers along each axis. Students can graph their data in less than a minute using a colored marker.