Education Technology

Science: Forensics Case 8 - No Dumping: Using soil characteristics to link suspects to a crime scene

by Texas Instruments


In this activity, students measure pH, conductivity, and water absorbency of different samples of soil. They use these characteristic properties to identify soil samples. They use the physical and chemical characteristics of soil samples collected from suspects to determine whether a suspect had been at a scene of crime.

Key Steps

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    Absorbancy is measured in how many mL of water that 50 grams of the soil sample can retain out of 100 mL of water poured into it. Four samples are compared with the sample gathered at the crime scene.

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    Similarly the conductivity of the four samples is measured in microsiemens and compared with the conductivity of the soil gathered at the crime scene.

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    Solutions of the soil samples are measured for their level of pH.  Students also look at the physical appearance of the samples to identify the sample that shares properties with the sample collected at the crime scene.