Materials

• Shoe box with lid
• 100 cubes
• Data table (included)

Extensions

1. Explain that several real chemical elements are used as atomic clocks - Uranium 238, Carbon 14, Potassium 40, etc., and that each is useful for determining the ages of particular kinds of rocks or minerals of a given span of time, e.g., Carbon 14 can be used for relatively young rocks (generally less than 55,000 years), whereas Uranium 238 can be used for very old rocks or minerals (more than 1 billion years).
2. Have students research two early methods for determining the age of the earth based on the salinity of the oceans and the cooling history of the earth.
3. Have students research methods scientists used to date rocks that were brought back from the moon.
4. Have the students research the term isotope. How does this relate to, and what are the hazards associated with Radon?