Education Technology

# Activities

• ##### Subject Area

• Math: Algebra I: Exponential Functions
• Science: Forensics: Time of death (rate of decay)

6-8

60 Minutes

• ##### Device
• TI-73 Explorer™
• ##### Other Materials
This is Activity 12 from the EXPLORATIONS Book:
Activities for Algebra with the TI-73.

The following materials are required for this activity:
• Small potato
• Pot with boiling water
• Celsius thermometer

## Murder in the First Degree - The Death of Mr. Spud

#### Activity Overview

Students model the process of cooling and use a cooling curve to simulate a forensic scenario to predict the time of death. They use technology to find an exponential plot.

#### Before the Activity

• Set up the calculator for data collection
• See the attached PDF file for detailed instructions for this activity
• Print pages 167 - 175 from the attached PDF file for your class
• #### During the Activity

Distribute the pages to the class.

• Insert a thermometer inside a hot potato and place the potato in cold water
• Record the temperature
• Enter the time and the temperature as lists
• Set up a scatter plot and model the data by graphing a line of best fit using exponential regression
• Record the temperature of another hot potato that has been cooled
• Use the graph to determine the time when the potato was removed from the hot water
• Understand how forensic study of body temperature of a corpse facilitates calculation of the time of death
• #### After the Activity

Students will complete the Data Collection and Analysis page and answer questions.

Review student results:

• As a class, discuss questions that appeared to be more challenging
• Re-teach concepts as necessary