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Lesson 3: GeoSleuth Murder Mystery

Overview This murder mystery introduces both the nature of scientific inquiry and important geologic concepts in a very student-friendly, accessible manner.

Geology is a lot like detective work. The power of this exercise is that it exposes students to the main goals of geology and even some of the fundamental principles in a setting that they can understand -- a murder mystery. After the class explores the murder mystery, the teacher then shows a range of geologic photos that relate to features in the mystery.

I originally developed the exercise to begin the very first lecture of the semester in an college level introductory geology course for non-majors. More specifically, the course was taught at the community college level in a program inside San Quentin State Prison. Originally, we were apprehensive about teaching a murder mystery to students who may have committed a murder themselves. However, the students became very interested and excited in the exercise, enthusiastically participating. Once we established a list of agreed upon observations, they began arguing back and forth about theories and their interpretation of the evidence. The exercise was an overwhelming success. It has been tested from 4th grade through the college level, and can easily be adapted to any grade level. However, depending upon the age level of your students, a murder mystery may or may not be appropriate. Either way, don't glorify the violence. In fact, one possible scenario is that the man is not dead, but just spilled coffee, tripped and fell.



Graphic of GeoSleuth detective

Drawing of room for GeoSleuth detective

Top image: Cathy Grimaldi
Bottom image: Matthew d'Alessio, USGS
Learning Outcomes
  • Geologists reconstruct the sequence of events that shaped the present-day landscape by making observations.
  • Observations are different from interpretations. Observations are descriptions of things we see. Interpretations are stories about what happened that are based on the observations.
  • Events that happened in the past are similar to events that we observe today. They follow the same laws of physics.
Materials Presentation (either as overhead transparency or computer projector).
The activity is based around the GeoSleuth murder mystery drawing, shown below. You have two options:
  1. Recommended: Download a prepared presentation complete with the image, supplementary geologic images, and a teacher's guide.
    (Presentation: Powerpoint or Acrobat PDF ~ 3 MB; Teacher's Guide: Acrobat PDF, 1 MB).

    See the Downloads Page.

  2. Abridged: Click on the image and print it on a transparency.
Time Requirements One 50 minute class period
Drawing of room for GeoSleuth detective
Introducing the Activity Get students excited that today they are going to do something a little bit different. Today, they are going to solve a mystery!


Instructions
  1. Have students look at the photo for 1 minute silently by themselves.
  2. Ask students to list observations about the image. Write them down on the board as students give them. Be very clear about the difference between observations and interpretation and don't write any interpretations on the board.
  3. When you have collected all the observations, ask the class if everyone agrees with these observations.
  4. Now the fun begins. Ask for students to volunteer their interpretation about the sequence of events that happened.
  5. Let chaos reign for a few minutes as students argue competing theories.
  6. Summarize the different interpretations, highlighting the geologic principles that each theory depends upon (shown below).
  7. Show the geologic images from the Powerpoint presentation.
  8. Put the murder mystery image up and go over the geologic principles again.
  9. End class without giving them an answer about what really happened.

Closing the Activity It's key to end the activity by returning to the GeoSleuth murder mystery photo. You should not, however, give students a definitive answer to the mystery. That's part of the nature of science -- there is never a right answer. There is only a "best answer," meaning one that is most consistent with the observations and most likely to be true. Different scientists often disagree about which answer is best, even when looking at the same data. This is because data are often incomplete or have large uncertainty.
Students may point out that they could say more if this were a color picture. That's very similar to science as well -- if we had the technology to collect better data (in this case, color), we could say more about what happened. For example, is that a coffee or a blood stain? It makes a difference, but we can't tell from this picture. We may have to modify our interpretation when we collect these new data points.

Homework Students can write their own murder mystery, carefully trying to integrate clues that will give the reader evidence of the sequence of events leading up to the murder.
Science Standards: California
Investigation and Experiment ("Nature of Science" standards)
Gr3, Sc5. Gr4, Sc6. Gr5, Sc6. Gr6, Sc7. Gr7, Sc7. Gr8, Sc9. Gr9-12, Science Investigation. Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. (See individual subitems for each grade).

Gr7, Sc4. Evidence from rocks allows us to understand the evolution of life on Earth. As a basis for understanding this concept:

Gr7, Sc4a. Students know Earth processes today are similar to those that occurred in the past and slow geologic processes have large cumulative effects over long periods of time.

Gr7, Sc4c. Students know that the rock cycle includes the formation of new sediment and rocks and that rocks are often found in layers, with the oldest generally on the bottom.

Gr9-12, Bio8g.* Students know how several independent molecular clocks, calibrated against each other and combined with evidence from the fossil record, can help to estimate how long ago various groups of organisms diverged evolutionarily from one another.

 

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