Education Technology

Catch a Thief with a Scatterplot

Activity Overview

A scatterplot can be used to determine if a relationship exists when comparing two sets of data. Once a relationship has been determined, predictions are possible. Law enforcement officers rely on evidence to find and convict criminals. If officers find a "footprint" at the scene of a crime, measurements are carefully taken. From the print, the height of the suspect is predicted. In this activity, students will gather height and shoe length data to predict the height of the suspect.

Before the Activity

Students should be familiar with the TI-Nspire handheld prior to beginning the activity. The teacher should anchor yardsticks or meter sticks prior to arrival of students. A few yardsticks/meter sticks should be taped to the floor to allow students to measure foot length. Several sets of two yardsticks or meter sticks should be anchored (end-to-end) to the wall at various locations for convenience in measuring student height. Activity sheets should be printed, and an overhead transparency should be available to project data as students record foot length and height. The teacher may choose to project the Lists and Spreadsheets application from the TI-Nspire computer software and allow students to enter data as measurements are taken.

During the Activity

As students enter the room, the teacher should instruct students to place books on desks, then immediately begin to take measurements. Working in pairs is the most efficient method of gathering this data, but individual students who have been previously coached in measuring accurately may be assigned to stand at each station and take measurements for consistency in measurements. The students are to make a judgment about the height of a thief who left a shoeprint at the scene of a crime. Each student will collect and organize data, create a scatterplot, then determine a linear regression to describe the data, then make a judgment about the height of the unknown person. The TI-Nspire handheld file (with invalid data) download may be used as a modification, if needed. Students will enter valid data in the cells.