Water Erosion Lesson Plan Evaluation

            Our lesson plan involved three activities that demonstrated the effects of water erosion, which is the most powerful erosive force.  Through analyzing and discussing these activities with students we were able to define erosion, identify the main qualities associated with it, such as deposition and sediment transfer, and make a distinction between erosion and weathering.  The three activities included a study of beach erosion, the effect an objects weight has on its erosion, and erosion’s ability to change a landscape’s shape. 

            Both of our sessions were very successful.  Tess taught the first session and through her experience we found that the students had knowledge of the rock cycle and were knowledgeable about the basics of our lesson, understanding topics such as chemical and physical weathering.  Her students were very engaged in the activity and it was apparent that they enjoyed participating in the outcome of each activity.  Simple things such as letting the students pour water on the sand and having them press rocks into the clay proved to be very enjoyable for the students and it seemed to give the students a feel of ownership over what happened during the activity. 

            Based off of what I saw during Tess’ section and from her advice to use our erosion slideshow as a sponge activity I was able to change what I had planned to do during my lesson to better accommodate the students.  My group was very knowledgeable and one of the students was working on a project about the rock cycle so he jumped at the opportunity to share what he knew about how rocks form.  Because we learned from Tess’ lesson that the students had a grasp of the basic principles of what we were teaching I was able to tailor my lesson to speak more about deposition and sediment transfer than about the types of weathering, chemical and physical.  I also tried to incorporate more student involvement in the activities by allowing the students to prepare the second and third activities however they liked.  This led to some spills and a bit of a mess but the students seemed to enjoy the roles they played in the activities. 

            In our lesson we were able to incorporate some of the seven E’s model.  We begun our lesson by eliciting the students’ prior knowledge of erosion and of the situations we were mimicking in our activities with questions like, “have you studied the rock cycle in class?” and, “Have you ever been to a sandy beach?”  With these questions answered we were able to engage the students by proposing questions about or activities to them and letting the students discuss what they thought the outcome would be. 

            In consideration of the exploration of our lesson the students had a hand in the experimental design by pouring the sand and water and placing the rocks in the clay.  They also observed what happened as their classmates either added water to the trays or created artificial waves.  Before the activities were started each student was asked to independently come up with their hypothesis for what would occur in the experiment.  From these observations the students were asked to interpret the results of the activities.  For the explain portion of the seven E’s, after the students discussed the forces they observed and the effects the water had on sand and rock they were introduced to properties of erosion such as deposition.  From this introduction a third activity was set up and students were asked to explain what happened to the sediment in light of the new forces and terms that were discussed.  Elaboration was included in our lesson as part of a sponge activity, this activity included pictures of water erosion along with examples of other types of erosive forces such as ice and wind.  When students were shown representations of other forms of erosion such as glaciers, they were asked to apply their knowledge of water erosion to this new related situation. 

            Evaluation was done by asking questions to the students after each activity about what had just happened, what forces could be viewed, what on the macro scale could this small scale activity be an illustration of.  The evaluation mostly took place through formative questions. 

            For the final stage of extend there was not much opportunity to extend the lesson beyond the short time we had available with the students.  The only opportunity we had for students to extend the lesson was during the elaboration stage where they applied the knowledge of water erosion to other erosive forces. 


Presenters

            Matt Boccuti               mrb5127@psu.edu

            Tess DelBaggio           tcd5006@psu.edu

 

Grade Level and Topic

            6th-8th grade

            Water Erosion

 

Standards

            PA Academic Standards for Science and Technology (7th grade)

                        3.5.4-A Describe earth processes(e.g., rusting, weathering, erosion)

                        3.5.7-ADescribe the processes involved in the creation of geologic

features (e.g., folding, faulting, volcanism, sedimentation) and that

these processes seen today (e.g., erosion, weathering crustal plate

movement) are similar to those in the past.

 

Instructional Objectives

            -Differentiate between weathering and erosion as it relates to the normal and catastrophic movement of rocks and sand

            -Describe the difference between Chemical and Physical Weathering

            -Understand beach erosion and how water is the dominant force

 

Materials and Equipment

-2 five-inch deep pans

-Sand  

-Clay  

-Rocks and pebbles

-Water

 

Content Explanation

            Students will develop an understanding of basic weathering and erosion and differentiate between the two. They will learn about the most powerful type of erosion: water erosion or beach erosion. Students will learn of the dynamics behind beach erosion. In this lesson, students will design an experiment where they will be able to observe beach erosion. They will observe beach erosion by creating a tidal force. Students will also observe how the weight and composition of certain materials resist erosion and how the process of erosion reshapes the landscape due to deposition through sediment transportation. This will allow the students to understand beach erosion and differentiate it from weathering.

 

Administrative Considerations

            -Supervision while students pour water and make waves

 

 

 

 

Lesson

Engagement (2-3 min)

-Ask a diagnostic question about weathering and erosion.  Have you learned about the rock cycle? Have you ever been driving and noticed the “Falling Rock” signs? What do you think causes the rocks to fall? Weathering is the break off of rocks and Erosion is the falling of rocks.

Weathering is the decomposition of earth rocks, soils and their minerals through direct contact with the planet's atmosphere. Weathering occurs with no movement, and should not to be confused with erosion, which involves the movement and disintegration of rocks and minerals by agents such as water, ice, wind, and gravity. Two important classifications of weathering processes exist. Physical weathering involves the breakdown of rocks and soils through direct contact with atmospheric conditions such as heat, water, ice and pressure. The second classification, chemical weathering, involves the direct effect of atmospheric chemicals in the breakdown of rocks, soils and minerals.

Erosion: The picking up or physical removal of rock particles by an agent such as streams or glaciers.  Beach Erosion primarily occurs through the action of currents and waves but sea level tidal change can also play a role.

Explain dynamics of Beach Erosion:

Hydraulic action takes place when air in a joint is suddenly compressed by a wave closing the entrance of the joint. This then cracks it. Wave pounding is when the sheer energy of the wave hitting the cliff or rock breaks pieces off. Abrasion is caused by waves launching sea load at the cliff. It is the most effective and rapid form of beach erosion. Corrosion is the dissolving of rock by carbonic acid in sea water. Limestone cliffs are particularly vulnerable to this kind of erosion. Attrition is where particles/sea load carried by the waves are worn down as they hit each other and the cliffs. This then makes the material easier to wash away. The material ends up as shingle and sand.

Another significant source of erosion is bioerosion. Sediment is transported along the coast in the direction of the current. When the upcurrent amount of sediment is less than the amount being carried away, erosion occurs.

Exploration (12-15 min)

Activity (1): Water and Sand.

Structural question:  Has anyone ever been to a beach? Tell me two things you’ve noticed?  We are going to talk about how the sand moves.

-Demonstrate beach erosion.  Using a pan, make a sand pile at one end and pour water at the other end.  Slide the pan back and forth to create water movement to illustrate large-scale tidal motion. 

Ask: What is happening?

 

Erosion is a result of fluid flow.  Though air and ice are considered to exhibit fluid flow, water is the most powerful force of erosion.  Fluid flow refers to these materials tendencies to flow from one place or another due to different forces such as pressure or gravity.  As water in the form of rain accumulates on a hill or mountain it flows downward due to gravity.  This flowing water has a force associated with it which allows it to carry materials down with it that are light enough to be moved.  This is called sediment transport.

 

Activity (2&3): Water, Sand and Rocks in Sediment

Structural question:  Have you ever noticed at the beach how the tide goes out?  The shells and rocks stay in place and the larger masses such as the jetties are not moved but the sand and water move.  What is causing this action?

-Demonstrate resistance to erosion.  Form a mound of clay in a pan.  On the sloped mound put sand and small shells, tiny rocks/gravel.  Pour water down the mound making note of how far the small shell/rock particles travel in comparison to the sand.

Ask:  What is causing the sand to travel farther than the shells/rocks?  What is happening to the sand and the clay? 

 

-Demonstrate resistance of large/heavy objects to erosion.  In same pan as before have students press in larger rocks/coins into the clay to imitate heavy objects.  Put sand and small shells/gravel on clay mound as well.  Pour water over the mound and observe the movement of objects. 

Ask:  What is happening to the pressed in materials?  Why are the rocks not flowing with the water and other particles that were lying on top of the clay?

 

*Note:  Erosion is not only a destructive force.  As tectonic forces elevate the land and create mountains erosive forces wear away the newly formed elevated land and transports that material down and to the coastline of the land.  Here the process of deposition adds to the coast of the landmass.  As erosive forces transport eroded sediment it is deposited and overtime builds up layers of sediment.  This occurs when the erosive forces are no longer strong enough to carry weight and overcome the forces of gravity and friction acting on the eroded particles. 

Assessment/ Reinforcement (2-4 min)

Ask:  Can you think of other types of water erosion?  What are some erosion events that you witness in your regular life?  Based on what we now know about erosion how would weathering contribute to erosion events?