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On Wednesday we held our July workshop which was attended by 17 teachers.

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The Biology panel was particularly invested in their discussion of osmosis.  The stems of the ‘paw paw’ plant (shown below) look like giant straws.  They cut the ends of the straws vertically and placed one in each of salty water, water and MnO2 solution.

The results are shown here too.

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The water went out of the stem into the salty water in an attempt to even out the concentration of water on either side of the cell wall.  The water went into the stem cells from the water beaker to dilute the interior of the cell in attempt to equalize.  In the third sample the water went out of the solution, leaving the MnO2 (purple colour does not penetrate the stem).  This demonstrates the process of osmosis which controls the movement of water across cell membranes.

To the right you can see a potato that started with dry salt inside.  Can you guess which potato is in the pure water and which is in the salty water? It’s hard to see but the bottom left shows the salt still relatively dry while the bottom right shows the salt relatively wet.

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A great discussion ensued around the specific definition of the term ‘osmosis’.

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The physics panel was working on showing refraction and reflection with optical pins.  I’ve taught physics for some 24 years and had not seen the kind of analysis they were doing.  For example instead of showing that angle of reflection is equal to the angle of incidence in reflection, they were comparing the turn-back angle (the angle of deviation from the original path) to the incident angle.  Not really sure how I feel about this in terms of a useful relationship.  The analysis of the refraction exercise I still need to take a look at.  It was quite complex.

All the physics teachers were also quite involved and appreciated the chance to re-investigate these concepts together.

 

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