A crime has been committed. Can you catch the crook?
Arch patterns have ridges that start on one side of the print, rise toward the center, and leave on the OTHER side of the print. Arches have NO deltas (triangular pattern).
Delta - a triangular shape found in many prints. See above.
Ridge Ending - A ridge ends.
Lake (Enclosure on the diagram) - A ridge in the shape of a circle/ oval.
Bifurcation (fork) - One ridge splits to form two ridges.
Island - A very short ridge in the print pattern is not connected to any other ridge, much like an island floating by itself.
Image credit: https://goo.gl/zgEgTf
A latent print is a print which is left on a surface and cannot easily be seen. The procedure for lifting latent prints is:
Question: Is black ink really black ink?
Chromatography is a technique used for separating mixtures. We use a solvent (water) to separate different pigments which have been mixed to form black ink.
Capillary Action: The tendency of a liquid to be drawn upward. (chromatography)
Cast: A molded mass of plaster. (footprints and tire prints)
Chromatography: Separation of a mixture into its component parts. (chromatography)
Controlled variable: A variable which is kept constant and unchanging.
Evidence: The facts available for proving or supporting a notion.
Forensic: Of or used in a court of law.
Graphology: The study of handwriting. (graphology)
Hypothesis: A proposition or supposition made from know facts as the basis of an investigation: a "best guess" as to what will happen.
Interlocking weave: Fabric knitted with closely-interlocking stitches. (fabric analysis)
Investigation: A careful study of something in order to discover the facts about it.
Latent: Concealed; not clearly visible. (fingerprinting).
Litmus paper: A blue-coloured paper stained with litmus (made from lichen), that is turned red by an acidic substance, and restored to blue by an alkaline substance; a pH indicator. (soil analysis)
Manipulated variable: A variable which is changed to affect the results of an experiment.
Mnemonic: Designed to aid the memory.
Pigment: A substance that imparts colour to other materials. (chromatography)
Porosity: The degree to which an article is able to be permeated by water or air.
Prediction: A foretelling of what might be expected.
Responding variable: A variable which changes in response to another variable being manipulated.
Scenario: An imagined sequence of events.
Solvent: A substance (usually a liquid) that can dissolve other substances. (chromatography)
Synthetic: Human-made. (fabric analysis)
Understandings - Topic D: Evidence & Investigation
Students sharpen their skills in observing and interpreting what they see by investigating evidence of human and animal activity. They explore and analyze indoor and outdoor environments as they look for footprints, markings, evidence of disturbance and things that are left behind. Through these studies, students learn to pose questions, devise investigations, recognize patterns and discrepancies, and think logically about what they have observed.
General Learner Expectations
6-8 Apply observation and inference skills to recognize and interpret patterns and to distinguish a specific pattern from a group of similar patterns.
6-9 Apply knowledge of the properties and interactions of materials to the investigation and identification of a material sample.
Specific Learner Expectations