Guiding Questions: How would the different types of rock and geologic processes affect how the Ancestral Puebloans built their homes? How did the alcoves in Walnut Canyon form?
Critical Content: Weathering and erosion created the alcoves in Walnut Canyon that the Ancestral Puebloans built their homes in.
Student Objectives: Students will...
See downloadable .pdf under the materials section.
• PowerPoint presentation
• Earth colored modeling clay, using two shades of clay is recommended (4 oz. per student or small group)
• Sugar cubes (3-6 per group)
• 1 see-through container with about 8 holes poked in the bottom per student
• 1 container to catch draining water
• ½ cup of cool water.
• Spoons to pour water on the model
• Student worksheet for Geology Makes a Home for each student
1. Before starting the activity or showing the clay model have students predict and write down how they think the alcoves in Walnut Canyon formed and explain why they think this.
2. Have a rock layer model prepared, that hasn't had water poured on it, to show the students what they are going to make. Explain that they are making a small model of the Kaibab Limestone. Their model is like a small cut out of the Kaibab Limestone, which really covers hundreds of miles.
3. Have students work in groups of 3 or 4 to build the models. If needed, the teacher can also build a model to help guide the students while the students build their own models.
4. Using the darker clay mold a bottom clay layer about ¼ inch thick. Make sure the clay edge is pushed against the side of the container. See Figure 1.
5. Add the layer of sugar cubes making sure they are also pressed up against the container side as much as possible. See figures 1 and 2.
6. Mold the lighter clay around the back and about ¾ of the way up the sides of the sugar cube layer. The side clay should not touch the plastic container like the bottom layer does to leave an opening for water to flow through. See figure 2.
7. Using the darker clay mold a top layer and place it on top of the sugar cube layer. Make sure the front edge of clay is pressed against the container like the bottom layer of clay. See figures 1 and 2.
8. Use the toothpick to form holes and cracks that go all the way through the clay and to the sugar layer. It's important that the holes and cracks go all the way through the clay and to the sugar. Putting the holes and cracks in the front half of the clay model can help to show that not all of the softer rock is eroded and is still present in the limestone. See figure 3.
9. Have the students draw a picture on the worksheet of their rock layer model and label the picture. If you are short on time this step can be skipped.
10. Have the students predict what they think is going to happen to the sugar layer when the water is poured on top of the clay? They should write their predictions in the worksheet.
11. Slowly pour a small amount, about 2 spoonfuls at a time, of water on top of the clay. If the water does not pass through the clay have the students use their toothpick to make the holes deeper or add more holes to the upper layer of clay.
12. The students should observe and record what they see happening to the sugar as the water seeps through the holes and runs out the openings at the edge of the model. They will continue slowly pouring water on the model and recording observations until most of the sugar has dissolved or they are out of water.
13. After they are finished pouring the water have the students draw a picture of what their model looks like and label the picture.
14. The students will answer the questions in the "Drawing Conclusions" section of the student worksheet. The students can complete these independently and then follow with a whole class discussion, or the teacher can guide the students by having a class discussion about the questions and then have the students write their answers.
15. Slides seven and eight are of alcoves that are still forming today in Walnut Canyon. Slide seven shows an alcove that still has a lot of the softer limestone within it. The students should be able to see that it is eroding away from the harder limestone and a hole has even formed through the softer layer. Slide eight shows an area of softer limestone that is breaking into smaller pieces and eroding to form an alcove.
16. Slide ten, eleven, and twelve show buildings in Flagstaff that are made from rock. Close the lesson with a discussion about the benefits and challenges of using rock in modern buildings. Slide ten shows historic buildings in downtown Flagstaff that were built from the local rock types. Slide eleven shows the modern buildings and patio in Heritage Square in Flagstaff. Slide twelve shows Flagstaff homes that have used rock as building material. Some benefits of using rock as building material include; better insulation, fire resistance, a more stable structure, it's a natural material with no chemical additives, increased sustainability, etc. Some difficulties in using rock in modern building include; increased cost, heavier weight, takes longer to build with rock, etc.
The student worksheet should be collected and used to assess student learning in the lesson, particularly numbers 1, 9, 12, 13, 14, 15, and 16 on the worksheet. These questions address the student’s ability to make predictions and observations, record data, and draw conclusions based on observations.
This lesson plan was developed by 3rd grade teacher Caron Jones, as part of the Teacher-Ranger-Teacher program.