Sediment Sample Murder Investigation

Submitting Organization: Relay Graduate School of Education

Grade Levels: 9th Grade, 10th Grade 

Subject Area: Science

Standards Alignment: Next Generation Science Standards

This activity is designed to build toward the following NGSS performance expectation: HS-ESS2-5

Description of the Activity:

Students are given different sediment samples, each from the shoes of a different suspect in a murder investigation scenario. Students measure the grain size of sediments from each sample under a microscope, and then use this information to determine the depositional environment of each sample, including river velocity if applicable. Finally, using what they know about the location of the murder, students identify the murderer from among the suspects.

Discussion Questions:

  • What is the relationship between stream velocity and particle diameter?
  • Why is that the relationship?
  • How precisely are you able to measure a single sediment particle?
  • Is this a good proxy for the average grain size of the sample? Why or why not? 
  • How could you improve your measurements if this were an actual murder investigation?
  • What was the river’s velocity where that sediment was deposited? How do you know?
  • Which sample isn’t from a river? How do you know?
  • How would this sample compare to one that was located farther upstream/downstream? Why?  

Resources Needed:

  • Four different sediment samples (e.g., sands, silts, unsorted sediment)
  • Microscopes, slides, cover slips,
  • Water and droppers
  • Paper rulers
  • A graph showing the relationship between particle diameter and stream velocity

Link to further resource: