Anchor Phenomenon Ideas: Share an article about a recent landslide or another significant erosion event like the loss of the Mississippi River delta or this image of a changing river over time. Use the authentic questions students come up with to make connections throughout the unit.
Make it Relevant: Point out local examples of erosion and weathering throughout the unit to help to help students make connections to their learning. Go on a neighborhood walk or take pictures of local geologic features to share in class. We had incredibly high engagement when we asked students to solve the problem of an eroding hill outside our school doors. They researched, planned and solved the erosion problem!
Tips and Tricks: If students are interested, here is a great explanation of how Monument Valley (the opening photo) formed.
For question two, it may be helpful to mix a batch of plaster of Paris at the beginning of class. Students should attempt to completely bury a small, tied water balloon in the center of the plaster. After the plaster hardens, transfer to a freezer. As the water in the balloon freezes, it should expand and crack the surrounding plaster rock. This is a great demonstration of physical weathering - water works its way into cracks of rocks, freezes, expands and breaks the rock.
As students observe chemical weathering (question three) we expect the calcite in limestone to react with vinegar and create small bubbles. However, students may need a hand lens to observe the bubbles. Most samples of granite do not have enough calcite to cause a reaction. Quartz will not react with vinegar. Only limestone would be expected to change mass after reacting in vinegar. Chalk made with calcium carbonate will also react with vinegar and is a good demonstration of chemical weathering.
The best way for kids to learn about erosion is to observe it. If you do not have access to a standard stream table, try to make one with sand in a large bin. To reinforce student observations, share this time lapse video of a meandering stream.
If students are stuck on positive examples of erosion, point them to landforms like the grand canyon and monument valley. Erosion also recycles Earth's rock and mineral resources.
Extension Activity: Make connections with a local earth science professional to learn more about unique geologic features in your area. Challenge kids to learn about the earth beneath their feet and how it got there!