The Case of the Vanishing Gnome

Use the attached Activity Slides to facilitate the activities. Display slide 2 to introduce students to the lesson’s title. 

Pass out a copy of the attached Field Notes handout to each student. Move to slide 3 and explain to students that they will be investigating a crime scene. Explain that a crime has taken place and a beloved gnome has disappeared from the client’s garden. Pass out a copy of the attached Detective’s Letter handout to each student. Display slide 4 and show students the crime scene. Read the Detective’s Letter out loud and have students follow along. They should record observations about the crime scene and the scenario on the field note side of the handout as you read. Repeat information as needed so students have detailed notes.

Display slide 5 to introduce the suspects and the pieces of evidence collected. Have students add the new information to their field notes. 

Use slide 6 to provide students with information about the soil and trace evidence. Have students record what they learn in the Supplemental Notes column of their handout. Explain how soil gets transferred from one location to another. Transition to slide 7 and go over the types of tests that need to be done to compare soil types.

Move to slides 8–9 and go over the essential question and learning objectives.

Move to slide 10 and explain to students that they will be analyzing the soil samples from three different suspects. Pass out a copy of the attached Soil Investigation Lab Guide handout to each student. Display slide 11 and explain that they must sign out the evidence to maintain chain of custody. Ask students to select a group member to retrieve their evidence packets. 

Once all students have their materials, display slide 12 and invite students to start with the sedimentation test. While the sedimentation test sits, have students complete the physical test display slide 13 and have them start the physical characteristics of their sample: color, odor, texture, presence of plant material, and presence of inorganic material. Have students use the steps on the Soil Investigation Lab Guide and record their results in the table. Remind them to leave the crime scene column blank as they will test that soil separately. Once students have finished their physical characteristic observation, move to slide 14. Invite students to complete chemical characteristic observations using the Soil Investigation Lab Guide. Have students record their results in the table. Transition to slide 15 and invite students to return the remainder of their evidence and clean up their station. Have students return their materials and wipe down their lab area. Display slide 16 and facilitate a discussion about what information they found and how it will help them determine who the thief is.

Display slide 17 and explain to students that they are going to be testing the soil from the crime scene. They will use the same Soil Investigation Lab Guide as they did in the previous activity. Inform students they will now be recording their information in the last column for the crime scene. Move to slide 18 and have students collect the crime scene evidence. Remind students that they will be conducting the same investigations as they did the previous day. Display slide 19 and invite students to start the sedimentation test. While the sedimentation test sits, display slide 20 and have the students start the physical characteristics of their sample: color, odor, texture, presence of plant material, and presence of inorganic material. Once students have finished their physical characteristic observation, move to slide 21. Invite students to complete chemical characteristic observations. Remind students to record their results in the table. Transition to slide 22 and invite students to return the remainder of their evidence and clean up their station. 

Move to slide 23 and ask students to compare the results of the crime scene analysis to the samples from the suspects. Invite students that they need to decide who they are going to accuse of the crime. Move to slide 24 and introduce students to the Claim, Evidence, Reasoning (CER) strategy. Invite students to state who they believe committed the crime via the fill-in-the-blank statement on the slide, provide 2–3 pieces of evidence (specific pieces of evidence from the physical and chemical characteristics that matched), and a reasoning or justification for the claim (explanation of trace evidence and what it means and how it applies to this situation). Pass out a copy of the attached Claim, Evidence and Reasoning (CER) handout to each student.

Ask students to share their CER with a partner. Then invite students to share their CERs with the whole group. Move to slide 25 and inform students who the criminal really was! Progress the slide deck once to reveal the thief on slide 25.

Move to slide 26 and invite students to create a presentation about soil investigating and two careers. Inform students they are going to look for one forensic career to present on as well as one career that involves testing soil (which does not need to be forensics-related). Pass out a copy of the attached Career Presentation Guide handout to each student. Referencing the handout, briefly walk students through requirements for their presentations. Encourage students to use the provided rubric on the Career Presentation Guide as creating their presentations. Provide students with the following link: aafs.org/careers-forensic-science.

Provide students time to search for a career that involves soil.

Display slide 28, and inform students that as their peers present their presentation they need to take note on the back of their Career Presentation Guide handout about two careers they learned about. Introduce a modified version of the SIT (Surprising, Interesting, Troubling) strategy. Inform students they will write down one surprising, interesting, and thought-provoking thing they learned about each of the careers they choose to record.