Warm Up Objective: Scientists will describe tool mark impressions by taking notes and analyzing tool mark impressions. What is the topic? What will you be doing? Why is this important? How will you know if you have done well?

Warm Up Objective: Scientists will describe tool mark impressions by taking notes and analyzing tool mark impressions. What is the topic? Tool mark impression evidence What will you be doing? Taking notes, analyzing tool marks Why is this important? Evidence; future career choice How will you know if you have done well? Able to describe tool mark impression evidence; analyzed tool marks accurately

Tool Mark Evidence Certain defects or patterns may be left on a tool when it is made or used, which can be used to find matches between evidence at a crime scene and tools or objects found at a suspect’s home. Tool marks can be classified two ways: Impressions – As a tool hits a softer surface, the shape of the tool and imperfections in its surface may be left behind as an impression. Scratches – As a tool moves across a surface, it may leave ridges or striations behind. NOTE: Some tool marks are a combination of both types. Features to analyze: Dimensions of the impression Ridges or striation patterns Defects, such as nicks and chips Paint chips or metal shards left on a tool   Images: http://geradts.com/html/Documents/structured_files/image004.jpg and http://www.maine.gov/dps/msp/criminal_investigation/crimelab/images/toolmarks1.jpg

Tool Mark Impressions Activity For each tool: Choose a clay and tool. Place the clay on the paper plate. Carefully hit the clay. Draw and describe the impression left. Smooth out the clay. Scratch the clay. Draw and describe the scratch left. Smooth the clay between each tool.

Tool Impression Picture/Description Scratch Picture/Description Hammer Adjustable Wrench Groove Joint Pliers Long-Nose Pliers Slotted Screwdriver Phillips Screwdriver (Bonus) Diagonal pliers

Analysis How can tool marks help investigators? Today, you used clay to represent a softer surface. Would the tool mark impressions and scratches on a harder surface such as wood or metal be similar or very different? Explain your reasoning.

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