February 10, 2010

Click the thumbnail below to see a graph showing the total transpired water  from all classes.

      When we observed our transpiration experiment today, we discovered a lot of  water had condensed on the sides of the plastic bags.  The plants that did not get watered did not produce as much water.  After observing the condensation on the sides of the bags, we used a balance to determine the mass of the transpired water.  Some students remembered a lesson from earlier in the year and were able to determine the volume of water in milliliters as well as the mass. The graph on the left shows the total for all of the third grade.
      And we learned about the openings (stomata) in the leaves that allow gases to enter and exit plants.  We prepared slides of the lower epidermis of corn and bean leaves and we were able to identify some stomata when we viewed these slides with a projecting microscope.
      In a subsequent lesson, we'll explore more thoroughly detail how transpiring plants affect the water cycle.
     This activity ties in with photosynthesis, leaf venation and the carbon dioxide-oxygen cycle that we will be studying soon. 

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