Earth's outer core consists of liquid metal, mainly iron and nickel. Due to the intense heat emanating from the solid metal inner core, convection currents are created in the molten metal of the outer core. Convection currents occur when the liquid metal of the outer core is heated, becomes less dense, and rises, as the molten metal rises away from the heat of the inner core, it cools, becomes denser, and sinks. These continuous convection cycles, along with the force created by Earth's rotation, generate electric currents which produce Earth's magnetic field. Although it is not necessary for students to possess this background information to complete this inquiry-based lesson, it would be beneficial to introduce these concepts to students before teaching this lesson. Alternatively, the teacher could extend this lesson by teaching these concepts after the inquiry.
This video clip provides information about the magnetic field created by the outer core: "The Mystery of the Earth's Core Explained" from DNews on youtube.com
Students should have a basic understanding of magnetism and know that magnetized objects can be attracted to or repelled from each other. Students should also know that the Earth is similar to a magnet, in that it has two poles: one that is positively charged and one that is negatively charged. If students do not have experience with the forces of magnetism, it would be helpful for the teacher to allow students to explore the attracting and repelling forces of dipole magnets.