Friday, October 2, 2015

Changes to our Land

This week we began to discuss changes to land. First, we talked about what kinds of changes can happen to our land. We discussed the meaning of weathering, erosion, and deposition. In 4th grade we focus on changes caused by wind, water, and ice, and do investigations that show how each can affect the land. 

We started with our investigation of wind. The kids made a sand dune in their box lids, trying to make the dune come to a point as much as possible. They then predicted what would happen when the wind (the kids blowing through straws) hit the sand. Most thought the sand would move to the other end of the box, forming a new dune. When they blew the wind, however, they notices the sand really just spread all over the box. We discussed why this happened, focusing on the size of the sand particles in relation to where they landed. We also talked about why the particles didn't form another dune. The kids came to the conclusion is was because the box was too slippery, so the particles just blew around all over the box lid. We did notice a stronger stream of air was needed to move the larger particles. We finished up by looking at some really cool pictures of wind erosion. We discussed how wind can cause erosion:  by picking up the particles (just like our experiment) and slamming them into objects such as rocks. Eventually, the rock is going to wear down from repeatedly being hit by sediment.