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27th February 2017
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27th February 2017

The dancing raisin

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Abel Paul Kannieappan urges teachers to engage learners in creative classroom activities to stimulate critical thinking

Want to get your learners to participate in your lesson? Do something different. Involve them actively. Faraday used this strategy in the 1880s. You can too by using “a discrepant event”.

A discrepant event tends to surprise, startle, puzzle, or astonish. It piques one’s interest and curiosity and leaves one wanting to know more about the event.

Teachers can use it as a demonstration or group activity, followed by discussion. It’s great to introduce a new section, engage learners in science processes, stimulate critical thinking or just make learning fun.

One such discrepant event is the quaint dancing raisin experiment. It works well in any grade and for any subject. It gets learners involved and excited — teachers too! This is how to go about it:

Get learners to bring the following to class:

  • A colourless soda drink e.g. a can of Sprite or baking soda in
  • A clear, tall tumbler
  • Raisins (fresh raisins for best results)

The learners can follow instructions from a worksheet or you could just instruct them to drop about seven raisins into the tumbler of the soda drink. Notice their smiles, gesticulations and animated discussions.

Then the unbelievable happens!

The raisins move UP and DOWN! On their own!

You will find the learners trying to explain what happened without you even asking them to.

The following questions can be asked:

  • Describe what happened.
  • Describe the movement of the raisins.
  • Why do the raisins move up and down?

Raisins have a greater density than the liquid. Initially they sink to the bottom of the glass. Carbon dioxide bubbles stick to the rough surface of the raisins, and they move up the tumbler due to the increase in buoyancy. At the top of the tumbler the bubbles burst and the carbon dioxide escapes, so the raisins loses their buoyancy and sink. Bubbles form on the raisin and the process starts all over again. This rising and sinking of the raisins continues until most of the carbon dioxide has escaped from the liquid.

The introduction of some upbeat music like Bruno Mars’s Uptown Funk will engage learners to move a bit like the raisins, making this lesson even more exciting.

Be like Faraday — use a discrepant event in your next lesson and make learning a “fun experience”.

Examples of lessons that this experiment can be used in:

  • Physical Science/N S/Technology/Maths — density and buoyancy;
  • Geography, English, Afrikaans — boat and plane disasters;
  • Hospitality and Consumer Studies — baking with raisins;
  • Engineering Graphics and Design — designing to remain

Examples of discrepant events and strategies for using them in the classroom can be found on the following site: Strategies for Teaching Science, Levels K-5.

https://books.google.co.za/books?isbn=142580649X

A video of the Dancing Raisin Experiment can be found at: https://www.youtube.com/watch?v=mEGCvj977_

Or just Google discrepant experiments for loads of examples and information.

Abel Paul Kannieappan lectures, conducts workshops, and has won numerous teaching awards. He is currently teaching Physical Science at Strelitzia Secondary, Durban in KwaZulu-Natal

 

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