Greendale 5th Graders Study Erosion

The fifth graders at Greendale Elementary School just finished studying about rocks.  Some of our key concepts included erosion, weathering, deposition and cementation.  In order for students to better understand the concept of erosion, we did an experiment with three plastic bottles and a lot of dirt!  One of the bottles consisted of nothing but dirt.  The second bottle consisted of dirt topped with leaves and sticks.  The third bottle consisted of dirt, but grass was rooted within the dirt.  The students put water in the bottles.  We took the caps, or lids, off of the plastic bottles and allowed the water to drain out.  As the water drained, it was caught by clear, plastic cups.  Each clear, plastic cup, due to the different content inside the bottles, produced different results.  The bottle that consisted of dirt had very dark water.  The bottle that consisted of dirt, leaves and sticks had semi-dark water, but not as dark as the previously mentioned bottle.  Lastly, the bottle that consisted of rooted grass and dirt had a much clearer water.  We determined that, because the grass’s roots held the dirt in place, it was more difficult for the dirt to be eroded and washed into the clear, plastic cup.  On the other hand, the bottle that consisted of nothing but dirt had nothing to keep the dirt from eroding.