Name: ___________________________
Date: __________________
Ms. Kim PBS Lab
Activity 1.1.4: Examining the Evidence
Station 1 – Shoeprints:
The shoeprint found at the crime scene belongs to: _______________
Explain your reasoning:
Station 2 – Fingerprints:
The ridge pattern category for Alex Garcia:
The ridge pattern category for Doug Greene:
The ridge pattern category for Erica Piedmont:
The ridge pattern category for Lucy Leffingwell:
The ridge pattern category for Anna Garcia:
The ridge pattern category for the fingerprint obtained at the crime scene: (see next page)
© 2013 Project Lead The Way, Inc.
PBS Activity 1.1.4 Student Response Sheet – Page 1
Circle and identify 10 minutiae on the fingerprint obtained at the crime scene below:
The fingerprint found at the crime scene belongs to: _________________
Explain your reasoning:
Station 3 – Hair:
The hair found at the crime scene belongs to: ___________________
Explain your reasoning: (must include terms cortex and medulla in answer)
© 2013 Project Lead The Way, Inc.
PBS Activity 1.1.4 Student Response Sheet – Page 2
Station 4 – Blood Type:
Background
Each person has one of four main blood types: Type A, Type B, Type AB, and Type O. The differences
between these blood types are due to the presence or absence of particular protein molecules called
antigens located on the surface of red blood cells and antibodies circulating in the liquid portion of blood
called plasma. Forensics uses these blood types, also called the ABO System, to link potential suspects to
the crime scene. However, because many people have the same blood type, the blood type alone cannot
be used as a definitive identification test. In order to definitively determine identity, further tests, such as
DNA testing, must be completed.
Evidence
Materials:
 Blood Typing Kit
o Simulated blood samples
o Anti-A serum
o Anti-B serum
o Blood typing slides
o Mixing sticks
Procedure:
1. Put on safety goggles.
2. Working on one sample at a time, place two drops of simulated blood in the A and the B wells of a
clean blood typing slide.
3. Place two drops of Anti-A serum in the well labeled A.
4. Place two drops of Anti-B serum in the well labeled B.
5. Using a separate mixing stick for each well, mix the simulated blood and antiserum for approximately
ten seconds.
6. Carefully examine each well to see if the blood has clumped. If clumping has occurred, place a “+” in
the appropriate box in the table on the Student Response Sheet.
7. Using a fresh tray for each sample, repeat all steps to determine whose blood matches the blood found
at the scene.
Fill in the following chart with a “+” if clumping occurred or a “-“ is there was no clumping:
Blood Sample:
Clumping with Anti-A Serum:
Clumping with Anti-B Serum:
Blood found at scene
Anna Garcia
Alex Garcia
Doug Greene
Erica Piedmont
Lucy Leffingwell
Blood Found at the Crime Scene might belong to: __________________
Explain your reasoning:
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PBS Activity 1.1.4 Student Response Sheet – Page 3
Station 5: Identifying an Unknown Substance
Four unmarked, white pills were found at the scene of the crime. It is your job to take on the role of a
forensic chemist to identify the unknown substance. Forensic chemists use two categories of tests to
analyze drugs and other unknown substances: presumptive tests and confirmatory tests. Presumptive
tests, such as colorimetric tests, indicate which type of substance is present but cannot specifically
identify the substance. Confirmatory tests, such as gas chromatography and mass spectrometry, are
specific tests that can determine the exact identity of the substance. In this activity you will perform
simple simulated tests to identify the unknown substance found near Anna’s body. Before you begin
your chemical analysis, you grind the pills into powder in order to conduct your investigation. Follow
the steps below to determine the identity of the unknown pills.
1. Put on gloves and safety glasses.
2. Measure 0.5 grams of Cocaine* into a clean weighing dish. Do this again into two other clean
weighing dishes. Make sure to label dishes appropriately. Alternatively, your teacher may have
you use a well plate instead of weighing dishes.
3. Study each substance. Examine what each substance looks like (i.e., What color and texture
does it have? Does it have large or small grains?). Record your observations in the data table
of your Student Response Sheet.
4. Examine the feel of each substance. Do this by rubbing each substance between your fingers.
Record your observations on your Student Response Sheet.
5. Determine whether any of the substances have an odor. Note: Never smell any unknown
substance directly. Use a cupped hand to waft a small sample toward your nose. Record your
observations on your Student Response Sheet.
6. Repeat Step 2 for the Acetylsalicylic Acid*, Methamphetamine*, Ecstasy*, and the unknown
substance.
7. Using a clean transfer pipet, carefully place two drops of Indicator 1 on each individual powder.
Observe what happens to each powder. Record your observations on your Student Response
Sheet.
8. Using new transfer pipets, repeat Step 12 with Indicator 2 and Indicator 3. Record your
observations on your Student Response Sheet.
9. Clean your lab bench.
10. Carefully remove your gloves using what you learned in the Personal Protection Equipment
Presentation.
11. Record the conclusions of your experiment on your Student Response Sheet.
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PBS Activity 1.1.4 Student Response Sheet – Page 4
Substance:
Appearance:
Texture:
Reaction to
Indicator 1:
Reaction to
Indicator 2:
Reaction to
Indicator 3:
Cocaine*
Acetylsalicylic Acid
(aspirin)*
Methamphetamine*
Ecstasy*
Unknown
Substance
*All substances are simulated
The unknown substance is: ______________________________________
Explain your reasoning:
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PBS Activity 1.1.4 Student Response Sheet – Page 5