Discrepant events and Demonstrations

1. Discrepant events and Demonstrations B. Law Unionville High School benjamin.law@yrdsb.edu.on.ca

2. Demonstration is a scientific experiment carried out for the purposes of demonstrating scientific principles. Students may have learned about the scientific principles before seeing the demonstration.

3. Discrepantevent is one that does not appear to follow basic “rules of nature”. Outcome of a discrepant event is unexpected or contrary to what one would have predicted.

4. There is no guarantee of learning when students observe or experience discrepant events. (They may have ignored or rejected it) • Some strategies are recommended: • predict the outcome; • construct one or more theoretical explanations; • observe the outcome; • modify the theoretical explanation; • evaluate competing explanations;

5. Safety comes first in both discrepant event or demonstration

6. (A-1) Singing plastic tubes Material: plastic vacuum tube / tubes from dollar store [Related to: Gr. 11 physics – sound unit] High pitch sound is produced when swirling a long plastic tube

7. (A-2) Blue Bottle demonstration - The solution will turn blue when you shake it. It will turn back to colorless after a short while Materials: Dextrose, Potassium Hydroxide, methelene blue indicator [Related to: Gr. 9/10 Science – Chemistry unit] Explanation: http://jchemed.chem.wisc.edu/JCESoft/CCA/CCA3/MAIN/BOTL/PAGE1.HTM

8. (A-3) Needle-proof balloon – A normal party balloon will not pop even a sharp needle is inserted into it. • Materials: Syringe/needle , balloons • [Related to: Gr. 9/10 Science – Chemistry unit]

9. (A-4) Fireproof balloon – A normal party balloon will not pop when it is placed above a burning candle. • Materials: Candle, Balloon (with water inside), retort stand and ring clamp. • [Related to: Gr. 9/10 Science – Chemistry unit]

10. (A-5) Colorful fireball – Fireballs in different colors will be produced when spraying the solution on a burning candle. • Materials: Spray bottles, Solution contains mineral nitrates and alcohol • [Related to: Gr. 9/10 Science – Chemistry unit]

11. (A-6) Isopropanol / Ethanol in pop bottle – vigorous combustion reaction can be observed • Materials: Isopropanol / Ethanol, dry 2L pop bottles, candle • [Related to: Gr. 9/10 Science – Chemistry unit]

12. (A-7) Isopropanol / Ethanol in big water bottle --vigorous combustion reaction can be observed • Materials: Isopropanol / Ethanol, Empty distilled water bottle (large size) • [Related to: Gr. 9/10 Science – Chemistry unit]

13. (A-8) Is it illegal to burn this paper bill? – Paper bill can not be burnt when it is soaked with 50/50 rubbing alcohol. Materials: Isopropanol, $5 paper bill, candle [Related to: Gr. 9/10 Science – Chemistry unit]

14. (A-9) Water “fall” ? – Good way to demonstrate the force between water molecules (surface tension) in particle theory. • Materials: Erlenmeyer flask , wire mesh, water • [Related to: Gr. 9 Science – Chemistry unit]

15. (A-10) CCD – Infra-red detector – IR beam can be detected by using a digital camera/video camera. Make the invisible become visible. • Materials: Any remote control, Video camera / Digital camera ,TV/ LCD projector with video input • [Related to: Gr. 11 Physics – Optics unit]

16. (A-11) Antigravity coffee can Materials: Large Coffee can, 1 kg mass, duct tape [Related to: Gr. 12 Physics – Energy unit]

17. (B-1) Hammering a nail into a wood over head (Newton’s 1st law) Materials: Few text books, block of wood, nail and hammer. [Related to: Gr. 11 Physics – Dynamics unit]

18. (B-2) Hydrogen Rocket – Newton’s 3rd Law • Materials: Empty Pringles’ can, Sulfuric acid, Zinc metal, Candle. • [Related to: Gr. 11 Physics – Dynamics unit]

19. (B-3) Few Bernoulli’s principle demonstrations (escaping egg, jumping coins, suspending ping pong ball, suspending squash ball) • Materials: raw eggs, small paper cups, coins, 250ml beaker, ping-pong balls, squash balls, hair dryer and leave blower. • [Related to: Gr. 12 Physics – Dynamics unit]

20. (B-4) Centripetal force demonstration • Materials: Wooden stage with strings attached to it, bucket with water • [Related to: Gr. 12 Physics – Dynamics unit]

21. (C-1) That’s a cool pen holder • Materials: Erlenmeyer flask, party balloon, electric kettle, beaker with cold water • [Related to: Gr. 9/10 Science – Chemistry unit]

22. (C-2) Sacrificing Gummy Bear Materials: Sodium Chlorate (KClO3), large clean Pyrex test tube, retort stand and test tube clamp, one gummy bear, Bunsen burner. [Related to: Gr. 9/10 Science – Chemistry unit, Gr. 11/12 Physics – Energy unit] Explanation: http://www.woodrow.org/teachers/chemistry/institutes/1988/gummybear.htm

23. (C-3) Density demonstration – suspending soap bubbles in a fish tank Materials: Empty fish tank, baking soda, a bottle of vinegar, soap bubbles solution. [Related to: Gr. 9/10 Science – Chemistry unit]

24. (C-4) Dying of the fire dragon -- Methane gas + Soap bobbles • Materials: Methane gas (Bunsen burner gas), soap bubbles solution • [Related to: Gr. 9/10 Science – Chemistry unit] Extra Safety Note: Wet your hands prior to handling the soap bubbles before burning

25. (C-5) Sparkling finger -- Lighting up Bunsen burner using index finger Materials: Van de graaff generator, short plastic stool (or inverted recycling bin), Bunsen burner [Related to: Gr. 9/10 Science – Chemistry unit, Gr. 11/12 Physics – Electricity unit]

26. THE END Tips: Try the demonstrations/discrepant events before showing students!

27. benjamin.law@yrdsb.edu.on.ca