Discrepant Events or Activities to probe misconceptions

Discrepant events are perceived as illogical or not possible.They differ from challenges, which are usually thought of as solveable.

  1. Demonstrate a Cartesian Diver. Pop bottle and eye dropper. Make a pop bottle and eye dropper system by inserting an eye dropper (that has enough air so it will barely float) into a plastic pop bottle, fill it with water, and cap on the cap. Demonstrate how when the pop bottle is squeezed the eye dropper sinks and when released the eye dropper floats. Ask why it sunk. Discuss how it sinks and floats. Make a model to explain its operation.
    Can extend the activity to make a pop bottle eye dropper system where the eye dropper is sunk and when squeeze it, it will float. A bottle with two droppers one that sinks and one that floats when squeezed. A system where a dropper sinks wen a glass containeris squeezed. A system where the dropper floats when a glass container is squeezed.
  2. Hold a jar (baby food) with two holes in the lid under water and rotate it so it will and won't leak. Ask what makes the difference. When does water go in and when does the water not? Does the size of hole make a difference? Number of holes? Position of the holes?
  3. If two pieces of paper (8.5 X 11 inches) are made into cylinders by rolling one the long way and the other the short way. Which cylinder will hold more rice (have the greatest volume)?
  4. Put a needle through a balloon without the balloon popping.
  5. Lift an ice cube with a piece of string. Materials: string, ice cube, salt
  6. Stick and newspaper. Can the stick be broken with out the newspaper flying off?
  7. Boil water in a paper cup over a flame.
  8. Fill one graduated cylinder with 50 ml of alcohol. Fill another graduated cylinder with 50 ml of water. Predict the volume of liquid if the two are mixed in a third 100 ml graduated cylinder.
  9. Can the belt hook balance a belt on the edge of the table? On your finger tip?
  10. Stick with two nails, equal size and mass spheres on either side of the nails. Strike the side of the stick with an object so that one sphere will fall straight to the floor and the other sphere will be pushed across the room. Which sphere will hit the floor first?

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  11. Plastic bag half-filled with water. Can a pencil be stuck through the plastic bag?
  12. Make a cardboard circuit puzzle with a magnetic reed switch. Demonstrate the puzzle without a magnet and have the students make a model of the puzzle. Then demonstrate the puzzle with a magnet and have the students make a model of the puzzle which will explain their observations.
  13. Fill a can with three holes and masking tape over the holes with water. Have the students discuss what will happen? Remove the tape one piece at a time. Then put a lid on can and see what happens.
  14. Light a candle and lower a copper wire coil over the flame.
  15. Make layers of density liquids or float solids at different levels
  16. Can you blow up a balloon and keep it blown up without tieing it or holding it?

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  17. Float ice in water and alcohol
  18. Dampen a cloth with hot water. Spread it over the top of a tray. Put tissue paper triangles on top of cloth and watch what happens to the pieces of paper.
  19. Float a potato in sugar water or egg in salt water.
  20. Put a few drops of iodine into a plastic bag of water (freezer bags may not work). Lower the plastic bag into another container of water.
  21. Fill three cups three-fourths full: one hot water, one cold water, and medium water. Arrange the cups in a line with the medium in the center. Have students put their index fingers into the outside cups for twenty seconds, then put both fingers into the center cup.
  22. Make a container with a magnet in a false bottom (school milk container). Suspend the container from a stand. Float a paper clip under the bottom of the milk carton. How do you know there is a magnet in the container without taking it apart?
  23. Tin can return: Materials: Coffee can with two holes in each end, rubber band, washers.

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  24. Water machine: Materials: Aluminum cans, flexible drinking straw, silicon caulk, glass, water.

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  25. Put a glow toy, in the dark, into a clear container of warm water.
  26. Why does the box fall off the table? Materials: Aluminum pop cans, salt or dry sand, duct tape, box

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  27. Put a few drops of peppermint concentrate into a balloon and blow it up. Can you smell the peppermint? Did you spill some or how can it escape from the balloon?
  28. Baby food jar with a piece of steel wool inside and a balloon stretched taught across the top and fastened securely with a rubber band. After a few days why was there a change?
  29. Place an inverted glass over a lit candle and on to a pie plate with water. Why did the candle extinguish? Why did the water rise into the glass? What would happen if the candle was at a different height? What would happen if the candle was raised as it burned?
  30. Move water from one glass to another with a straw, but without using your mouth or touching the glass with anything.
  31. Take a glass and fill it with ice cubes. Then add water until adding more water will cause it to overflow. When the ice melts will it overflow, will the water level be the same, or will it be less?


See also Challenges

Dr. Robert Sweetland's notes
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