Reworking preconceptions on water movement through soil.
The demonstration will be designed to enable participants to experience reassessment of their own preconceptions and allow them to reflect on the etiology of these thoughts.
Students watch a video with a series of experiments on how water travels through soils (loam, sand, clay) and other materials such as aggregates and organics (https://www.youtube.com/watch?v=ego2FkuQwxc). The video is stopped several times to allow students to make predictions about what will happen, then they watch what does happen. Several of the experiments do not turn out as they predict. Students then examine why the water moves in the unpredicted way. They then apply this new knowledge to other situations in their everyday life, i.e. soaker hoses, draining wetlands etc.
Students are more engaged in the experiments shown in the movie. The first prediction is intuitive, and they hypothesize correctly, then next two are incorrectly predicted. But, by the later experiments, some students do change and predict the correct outcome based on the previous experiments. Students better understand how water moves in soil (seen in applied questions later in the course) but some cling to the more intuitive, incorrect line of reasoning. To address this, a discussion session will be added to discuss why their intuition was incorrect.
Target audience: college students in Soil Science, Hydrogeology, Foundation Engineering, and Ecology. High-school students in Earth Science and Environmental Science courses. Students need an understanding of adhesive and cohesive properties of water and capillary action before, or after watching the video.
I use this in Soil Science in the section on water and water movement. The first part is discussion based on a PowerPoint that includes the water cycle and the unique properties of water. We then watch the video. Students are assigned a worksheet for review and discussion.
Why It Works
The activity is effective because the students realize they do not intuitively know how water flows through different materials. This is a surprise, and makes them more engaged with the material.
Presentation MediaTeaching Handout Water Movement in Soils (Microsoft Word 2007 (.docx) 101kB Jul21 17)
Student - water movement through soil (Microsoft Word 2007 (.docx) 51kB Jul21 17)