Grade level

7. Erosion Patterns

Summary
This lesson is an extension of the GEMS guide: “River Cutters” by the Lawrence Hall of Science (see note below). In the GEMS curriculum, students are introduced to erosion by modeling the formation of rivers in tubs of diatomaceous earth, a silt-like substance into which meandering river channels and deltas form. This lesson builds off of the River Cutters activities by using a combination of sediment types in the models. They observe how gravel and large particles of sand remain in place whereas silt is washed downstream in fast flowing river channels. In contrast, where the water velocity slows as it reaches the newly forming bay, a beautiful silt-covered delta forms. These observations lead students to the conclusion that fast moving water picks up the smaller sediment particles and eventually deposits them in places where the water slows. Students can then take this theory to test it out in real world conditions at a local creek in the Sediment Study Project, observing sediments and water velocity at different sites along a creek’s length. The concept of how sediments are deposited becomes a core feature of subsequent geology lessons and investigations in which the environmental conditions surrounding the formation of large particled conglomerates may be differentiated from small particled shales and siltstones.

GEMS River Cutters

Special Note: This lesson plan is written with the assumption that students have some experience using the river models in the GEMS guide “River Cutters”, written by Cary Sneider and Katharine Barrett and produced by the Lawrence Hall of Science. In this guide, students make observations of rivers carved in just silt (diatomaceous earth), sequencing events in time, noticing patterns, recording information, and acquiring the terminology necessary to describe common erosion patterns. My students completed the first 5 sessions of River Cutters although completing the first 3 lessons is sufficient. So as not to infringe upon the copyright of the GEMS unit, only the extension activity is described here.


Project - Sediment Study

Summary
In this culminating project, students go out into the field and test their theories about erosion and sedimentation at a local creek. How are sediments distributed along the creek? Does it vary by location (the source, mid-stream, and the mouth)? Does it vary by the velocity of the current? Different classes can collect information for the different study areas. At a study site, they will draw maps, measure the velocity of the current, and collect sediment samples from the creek bed. These samples are analysed back in the classroom for the percent of different sediments they contain. Finally, students stand back and examine their data to try to make sense of the sediments they find. If it is not possible to bring students to a creek, there are many ways to bring the data to them. Collect the sediment samples yourself with photos and water velocity information OR use the Suspended Sediment Database to draw your conclusions. This USGS database provides stream flow and sediment information for over 1,500 rivers and creeks nationwide (see the Going Further section for more information on using the USGS’s database).


6. Topo Tour

Summary
Once students understand the basics of how to read and create a topographic map (see From Maps to Models lesson), students will study and label a topographic map of their local watershed. They will identify the creek closest to their school and mark the boundaries of their watershed. In the process, they practice recognizing hills, ridges, valleys, stream beds and other geographical features on a topographic map. Finally, students take their maps and walk a part of their watershed, matching their maps to their real world surroundings. If a walk through your neighborhood is not possible, the lesson can be conducted without the watershed walk. The watershed walk portion of this lesson may be combined with the Sediment Study Project.


5. From Maps to Models - Sources and Standards

Sources
Activity descriptions and ideas
I first learned how to make topo maps from Eric Muller of the Exploratorium’s Teacher Institute. I changed the method for making the topo map from the models but otherwise our activities are very similar. You can download his "To Topo Two" activity below or from his website with other stellar activities.


5. From Maps to Models

Summary
Most middle school students have not seen or used topographic maps before. Conceptually, it is difficult for kids to see how a 2 dimensional topo map represents elevation. In this activity, students learn how to create and read topo maps. By the end of the activity, they should be able to read a topo map and identify simple geographical features from a map. Teams of students mold a landform out of clay then place it into a clear plastic container. Water is added to the container in 1 cm intervals and students trace the “shoreline” of their model onto a transparency placed on the box lid. The resulting topo map is traded with another group who is then challenged to turn the 2 dimensional map back into a 3 dimensional landform. Several options are provided for creating the final model based on the materials available to the class. In fact, having more than one option of how to create the model often leads to greater understanding of how topo maps represent elevation.


Field Trip - Bay Model

Summary
This section will give you information to help you plan a field trip to the San Francisco Bay Model. The Bay Model is a working three-dimensional model of the San Francisco Bay and Delta areas. It fills 3 warehouse sized buildings and students who visit get a guided tour, observing the flow of the water, learning about how scientists use scale models, and leaving with the impression that the Bay is a very big place.

Field Trip - Save the Bay

Summary
This section will give you information to help you plan a field trip with Save the Bay. I brought 32 students to Arrowhead Marsh, a hidden wetland near the Oakland Airport, to meet up with extraordinary Save the Bay Instructors. The day was divided into two parts: 1) Canoeing – where we did water quality monitoring, explored the marsh with all our senses, and went on a wildlife scavenger hunt 2) Restoration – where we repotted 300 native plants, cleaned up the shoreline, and went for a walk on a boardwalk above the marsh. Students were able to explore a wetland up close and observe a leopard shark, feel the Bay’s muddy bottom, and listen to the endangered snowy plover.


Sub Plan - Bay Classroom Webquest

Summary
Students go on a web-quest for information on Save the Bay’s Bay Classroom website. They discover facts and information about the part of the San Francisco Bay, its history, the creatures that call it home, and ways they can help protect the bay. This easy activity requires little supervision and is thus offered as a great substitute teacher lesson plan or for one of those teaching days when you need a last minute lesson. Suggestions for making this lesson more interactive are provided.


4. San Francisco Bay Watershed


Summary


Students get an introduction to the San Francisco Bay watershed by studying a map of California. The concept of a watershed is solidified using the San Francisco Bay watershed as an example. Major geographical landmarks are identified on the map. Students then turn their hands into a portable map of the watershed. They discover how the water cycle determines the flows of water in different seasons, and therefore determines the utility of dams and reservoirs to even out the flow. In the process, students learn about the reasons the Bay is so important to California’s people, economy, and wildlife. This lesson may be extended into a history of the San Francisco Bay lesson.

Objectives
Can feel a sense of place and connectedness to other parts of the state.
Can identify the major landmarks in the San Francisco Bay watershed.
Can see similarities between very large watersheds (on a statewide level) and very small ones (on a neighborhood level).


3. Katrina Case Study

Summary
Through a demonstration, students learn about the balance between subsidence and flooding in the formation of a wetland. Students then watch a short 15 minute PBS video about the wetlands of Louisiana. They will discover how levee building and the subsequent loss of wetlands contributed to the severity of Hurricane Katrina’s effect on the city of New Orleans. Finally, the class holds a discussion geared towards environmental stewardship and habitat restoration.

Objectives
Can explain how subsidence and flooding contribute to the maintenance of wetlands.
Can explain how levees prevent flooding and exacerbate subsidence.
Can explain how wetlands protect shoreline from natural disasters such as hurricanes and flooding.
Hurricane Katrina Can discuss the goals of habitat restoration.
Can recognize the importance of environmental stewardship.

Vocabulary
Wetland
Soil compaction
Subsidence
Habitat restoration
Environmental stewardship