COMPOSITION OF THE EARTH

Use half-frozen apple juice to illustrate fractional crystallization e.g. presumed partitioning of elements between inner and outer cores, by having the class taste the difference in sugar concentration between the solid and liquid.

Illustrate effects of pressure by having students attempt to pull a plunger off a desk, and then consider pressures thousands and millions of times greater..

Increase of hydrostatic pressure with depth illustrated by difference in water flow through detergent bottle with holes drilled at various depths

Geiger counter illustrates concept of radioactivity, and is made (hopefully) memorable using banana or Gatorade (contain potassium sufficient for clear signal).