Science Olympiad Crime Busters (B) Hints, Tips, Things to Prep

Overview Story arc presents Table of Results suspects types of evidence which exhibit goes w/ which suspect Table of Results Evidence Powder Metal Liquid Hair Chro Crime Scene P1 P2 P3 P4 M1 M3 M4 M2 Suspect 1 Suspects Suspect 2 Suspect 3

Prep Pack the Student Kit see list in Rules ex: hand lens(es) ex: small containers (spot plates / well plates?) plural have enough to run all tests w/o washing waterproof box for dirty ex: paper towels does not specify all the same type pack plenty (include enough for cleanup) Read the rules… build the kit while practicing the tests

Categories of Exemplars Powders Metals Liquids Hair Fibers Chromatography DNA (results) Fingerprints Recyclable Plastics Shoe Prints / Tire Tracks Required Groups - 55% Optional Groups – 15% Analysis – 30%

Prep: Powders, Metals, Liquids Develop a Flowchart Practice the tests chart of results in binder count equipment needed for student kit

Prep - Powders Add Water Swells  Gelatin Bubbles  Alka-Seltzer Cloudy and Stinks  Yeast Dissolves  go to pH test Does not Dissolve  go to iodine test

Prep - Powders Dissolved  pH test Acid  Vitamin C Base  add vinegar Bubbles  Baking Soda No Bubbles Sodium Acetate Neutral  observe the crystals Cubic  Salt Hex  Sugar

Prep - Powders Did Not Dissolved  Iodine test No Change  Sand Brown / Tan  add vinegar Bubbles  Calcium Carbonate No Bubbles Calcium Sulfate Blue  observe original color White  Cornstarch Off-White  Flour

Prep - Metals Color Copper Magnet Iron HCl Zinc Tin Aluminum Magnesium Yellow/Orange Color Copper Other Attracts Magnet Iron Not Bubbles; Steam HCl Magnesium Bubbles; No Steam Zinc No Bubbles; Dents Easy Tin No Bubbles; No Dent Aluminum

Prep - Liquids Physical Characteristics & pH Liquid Odor Color Blue Litmus Red Litmus pH A/B/N Alcohol strong clear R 6 A Ammonia B 11-12 HydPer weak to B to R 0.5 - 6.5 Lemon weak fruit yellow 2 Vinegar 3 Water none 7 N

Prep - Hair Human Medullary index < 1/3 even distribution of pigment Hair Cross-Section Human Hairs

Prep - Hair Animal Medullary index > 1/2 Dog continuous medulla scales usually not visible ovoid bodies root is spade-like

Prep - Hair Animal Medullary index > 1/2 Cat uniserial medulla; very large spinous scales root looks frayed

Prep - Fibers Animal (Hair) Synthetic cuticle and/or madula smooth surface odd cross-section

Fiber – Burn Tests Synthetic Animal Vegetable shrinks from flame or melts Animal smolders smells like burning hair Vegetable irregular burn rate stinks

Prep - Polymers Density Dichotomous Key 2 5 4 6 1 Water 46% Isopropyl Alcohol Vegetable Oil 10% NaCl Saturated NaCl PP LDPE HDPE PS PETE PVC PC PMMA Unknown Polymer floats sinks 2 5 4 6 1

Prep - Chromatography Typical chromatograms

Optional - Fingerprints arch tented loop radial ulnar

Optional - Fingerprints whorl central pocket double loop accidental

Optional – DNA Chromatogram

Optional - Foot & Tire Prints visual comparison

Optional - Spatter Directionality Angle of Impact Droplet Size

Option – Soils compare composition microscopic examination soil triangle

Science Olympiad Crime Busters (B) Hints, Tips, Things to Prep