Purpose: This model clock demonstrates how scientists can tell the age of the Earth by examining radioactive ore. The clock can also be used as a timing device.
Materials: Two straight-sided bottles (such as baby bottles), two rubber stoppers (two-hole), and two very short pieces of glass tubing.
What to Do: Join the two stoppers together with glass tubing through each hole (for baby bottles the stoppers should be #7). Fill one of the bottles with water. Insert the stoppers and the other bottle as shown. Turn the “atomic time clock” over so the water slowly runs into the second bottle.