WA: Physical Science Forensics Unit

Forensics is one unit which dovetails well with Chemistry and Biology.  Our Science Camp had a forensics intro the year we had Anatomy Academy.  One of the parents at WA is a police officer.  I thought it might be fun for my Physical Science class to create a crime scene for the younger students with rotating lab stations.  In fact, this might be a fun family science night.  Chalk bodies on the floor, drape the room in crime scene tape, and mix up a batch of Fake Blood for the splatter lab!  If this is your first foray into forensics, It's Magic is an excellent introduction.

The Physical Science class needs some background, Crime Scene Basics and Guided Notes.  Three good labs for beginners are Ink Chromatography, Glass Chip Density, and Fingerprints (Fingerprint Analysis Sheet).  Next, Blood Splatter Lab or Blood Splatter Activity are introductions to terms and properties of bloodstains.

Now, one of my favorite forensic labs is blood type testing.  Here is one, Cheap Blood Testing, complete with a cheap recipe for fake blood, because many schools ban blood testing students; besides, the serums and kits are expensive.

 DNA Electrophoresis may be outside the scope of Middle School science; DNA Extraction, however, is easy and a terrific forensic activity for kids.  The key is to chill the alcohol and use fresh meat tenderizer.  This can be a great inquiry-based lab; it uses dry, split peas, which are much cheaper than strawberries-especially since I want the kids to do several trials to see which method produces the most DNA.  Instruct the kids to compare three different detergents or try using different concentrations of rubbing alcohol, or compare isopropyl alcohol with ethylene alcohol.  Try room temperature alcohol with chilled alcohol.  Vary the amount of salt.  Just help the kids to understand that they need to change just one variable at a time.

Once the kids have practiced these labs and are ready to lead the labs, it is time to set the scene.  Kids       will need practice managing clues.  Crime Scene (Teacher Notes, Crime Scene Map, and Student Guide) is a great way to help kids sort clues.