Using physical observations to guess the interior of a globe
This activity was selected for the On the Cutting Edge Reviewed Teaching Collection
This activity has received positive reviews in a peer review process involving five review categories. The five categories included in the process are
- Scientific Accuracy
- Alignment of Learning Goals, Activities, and Assessments
- Pedagogic Effectiveness
- Robustness (usability and dependability of all components)
- Completeness of the ActivitySheet web page
For more information about the peer review process itself, please see http://serc.carleton.edu/NAGTWorkshops/review.html.
This activity has benefited from input from faculty educators beyond the author through a review and suggestion process. This review took place as a part of a faculty professional development workshop where groups of faculty reviewed each others' activities and offered feedback and ideas for improvements. To learn more about the process On the Cutting Edge uses for activity review, see http://serc.carleton.edu/NAGTWorkshops/review.html.
This page first made public: Jul 31, 2007
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Description of the activity/assignment
Each globe has been designed by the instructor to highlight one or more aspects of geophysics. In the Acoustic Globe, various objects are added to the globe that will generate vibrations when the globe is shaken. These may include pennies, nuts, bolts, glass marbles, or ball bearings. The vibrations generated are analogous to seismic waves generated by a sledge hammer, a shot gun blast, or an earthquake. The seismic waves are recorded at the land surface by a seismometer, or in this case the students' ear drums, and an interpretation is generated. Advanced globes can contain cardboard dividers with small holes that allow the passage of all or some of the internal objects. Students can then interpret the internal structure of the globe.
In the Magnetic Globe, magnets or strips of iron are taped to the inside surface of the globe. The students will use magnets and paperclips to identify changes in the magnetic field of the globe caused by the heterogeneous composition of the surface of the globe, which is analogous to a magnetic survey. This globe could be combined with the Acoustic Globe if some of the objects inside the globe contain iron and some do not.
To create a Thermal Globe, the instructor can fix a gel cool pack to the inside wall of the globe and place the globe in a freezer until an hour before class. Students will used the strip thermometer to map regions of different temperature along the surface of the globe which may be used to infer convective processes occurring within the globe. This globe could easily be combined with either of the previous globes.
Finally, a Conductive Globe is designed by stringing the interior of the globe with wires of different compositions (copper, soldering wire, aluminum foil). The ends of each wire are connected iron nails which extend through the globe and are exposed on the globe surface. When the student completes the circuit using the wire, the 9 volt battery and the small light bulb, the light bulb will turn on. The intensity of the light will be different for each different type of conducting material. Through experimentation, the students can determine regions of homogeneous composition on the surface of the globe similar to an electrical conductivity or resistivity survey.
At the end of the exercise, each team will give an oral presentation to the class that describes their globe. Students should describe:
- the methods used to investigate the globe,
- the findings of their investigation; and
- their interpretation of the interior of the globe.
This activity has minimal/no quantitative component.