Safety Precautions: Perform under adult supervision. Wear safety goggles. Exercise caution when using a stove. The marble will be very hot for several minutes after it is placed in water.
Place a marble in a frying pan and heat for 10 minutes on the stove.
Using tongs, remove the marble from the pan and drop it into a cup of cold water.
Allow to cool for several minutes, then remove the marble.
As the marble is heated, it expands. When it is cooled, it contracts. If it contracts too rapidly, it will shatter. This is why it is not good idea to put water in a hot piece of glassware. Since the marble is spherical, it contracts equally in all directions, shattering the inside of the marble while still retaining its spherical shape.