This participatory demonstration of the influence of rigidity on the speed of seismic waves helps students understand the relationship between the speeds of seismic P and S waves and the rigidity (the resistance to shear deformation) and incompressibility (resistance to compression) of the medium. The demonstration requires only a watch or stopwatch. To create the waves, students stand side-to-side ... Full description.

This demonstration of average density uses understandable units of total mass and volume of the Earth. The required supplies are a can of beer or soda and a 1-pound bag of pretzels. By imagining, for instance, 4.4 bags of pretzels fitting into a beer/soda can, students can better visualize the average density of the Earth. Full description.

This demonstration uses a gyroscope (a bicycle wheel works well), string, and a turntable (optional) to show how the equatorial bulge of Earth causes precession. By balancing the spinning bicycle wheel on one hand, and pulling a string attached to the top axle with the other, the axis of the wheel traces out a circle (precesses). The site also explains how the moment of inertia is related to torque ... Full description.

This is a demonstration of the Core Shadow Zone of the Earth. Using a clear or translucent half-sphere held in front of a light source, the refracting properties of the core and how it generates the shadow zone on the surface are illustrated. Full description.

This demonstration of the magnetic field lines of Earth uses a bar magnet, iron filings, and a compass. The site explains how to measure the magnetic field of the Earth by measuring the direction a compass points from various points on the surface. There is also an explanation of why the north magnetic pole on Earth is actually, by definition, the south pole of a magnet. Full description.

The Curie temperature for iron is reached at about 20 km depth in the Earth, and the temperature is much higher at the outer boundary of the Earth's core so that the iron there is no longer ferromagnetic (the electron spins in the iron can no longer align). This demonstration will help students understand the magnetic field of the Earth, and can help explain the variation of the direction of the field ... Full description.

This demonstration of the Earth's magnetic field requires a DC motor, ammeter, electromagnet, and DC power supply or battery. The site explains the concept of a dynamo and how if an electrical conductor is in motion within a magnetic field, a current will be generated in the conductor, and if that current flows around in a loop, it will, in turn, generate a magnetic field. Full description.

In this activity, students work in teams to locate the epicenter of an earthquake using the time travel difference between the primary (P) and the secondary (S) waves. Teams work out that the time difference between the wave arrival times depends upon the distance of the monitoring station from the epicenter. To locate the earthquake they draw circles of the appropriate (scaled) radius from the monitoring ... Full description.

In this activity, students use magnetic field data and a map of the ocean floor around Iceland to observe how the direction of magnetization of the ocean floor varies. This links the magnetization of rocks with the theory of tectonic plates. As students complete the worksheet they will discover that the magnetic field of the Earth has flipped (the N pole becoming the S pole, and vice versa) many times ... Full description.

This demonstration shows how the Earth's magnetic field has flipped (the N pole becoming the S pole, and vice versa) many times through geological time. It also demonstrates that as tectonic plates move apart, new rock is formed and locks in the direction of the magnetic field at the time. Students should realize that the discovery of stripes of alternately normal and reversed-magnetized rocks forming ... Full description.