In this lesson, students play the role of toxicologists as they observe and conduct chemical tests on a variety of powders. The expertise of toxicologists regarding chemicals and their reactions is necessary to perform the many tests conducted during an investigation.
Toxicologists perform tests on body fluids and tissues, like organs, to determine if traces of drugs, alcohol, or poisons are in the body. Even hair and nails can contain traces of drugs. Although police officers may conduct very simple tests when there is an arrest, often the qualitative testing must happen at a more sophisticated level. If the police test indicates there is a significant likelihood that illegal drugs are present, then a blood or urine sample must be taken for further study.
Most of the testing that toxicologists conduct is related to driving-under-the-influence arrests. Special machines have been designed to conduct these tests. First, it must be determined that the sample does indeed contain drugs or alcohol. If drugs or alcohol are found, the exact amount present must be determined. The machines, similar to small robots, are able to vacuum up the sample, prepare them for testing, conduct the tests, and display the results on a computer!
In the following activities, students observe the properties of powders and crystals, record their observations, and then use them to determine the substance found at the crime scene.
The activities in this lesson address Next Generation Science Standards practices of Asking Questions and Defining Problems, Planning and Carrying Out Investigations, and Engaging in Argument from Evidence as well as disciplinary core idea PS1.A. In addition, they address Common Core State Standards CCSS.ELA-Literacy.CCRA.SL.1 and CCSS.ELA-Literacy.CCRA.SL.2. See the Standards Matrix included in the appendix for more detailed information.