This year for homeschool high school science my 15 year old chose to learn about Forensics, so we have had three other teens join us every other week to do some Forensics lab work. Thus far, we have worked with hair evidence, fiber evidence, and blood evidence. Along the way we have worked with a microscope, learned to prepare slides and operate the microscope, performed heat and chemical tests on fibers, learning a bit of chemistry, tested for blood type, and dissected an assortment of mammal organs.
This week and the previous session we were learning about glass evidence. The previous session involved examining a variety of glass fragments and learning a lot about reflective and refractive properties of glass, as well as about light and optics.
Above is some of the stuff we used the other week to explore reflection and refraction, as well as fluorescence -- homemade light box with slits, mirrors, a card with refraction angles marked, a combo black light/flashlight, and some books we were using.
This week we explored glass fracture patterns -- how a fractured pane can give us information of the sequence of bullets fired, types of bullets or projectiles, the angles of the shots, etc. We used certificate frames from the dollar store, which were shot with a variety of air soft guns, producing both radial and concentric fracturing typical of gun shots to glass. We kept the plastic on the frames and that held all the glass together so we could see the fractures. That was great, because we didn't have to carefully lift and tape up the panes to preserve the fracture patterns for our observations.
The frame above had a really good pattern of 4, possibly 5 shots, and the kids were able to deduce the order the shots were fired in from the patterns.