Students not only want to know how old a fossil is, but they want to know how that age was determined.
Some very straightforward principles are used to determine the age of fossils.
The teacher should tell the students that there are two basic principles used by geologists to determine the sequence of ages of rocks.
They are: Principle of superposition: Younger sedimentary rocks are deposited on top of older sedimentary rocks.
This first time of shaking represents one half life, and all those pieces of candy that have the printed M facing up represent a change to the daughter isotope.That chance of decay is very small, but it is always present and it never changes.In other words, the nuclei do not "wear out" or get "tired".4) To demonstrate how the rate of radioactive decay and the buildup of the resulting decay product is used in radiometric dating of rocks. (A single watch or clock for the entire class will do.) 6) Piece of paper marked TIME and indicating either 2, 4, 6, 8, or 10 minutes.5) To use radiometric dating and the principles of determining relative age to show how ages of rocks and fossils can be narrowed even if they cannot be dated radiometrically. 2) Large cup or other container in which M & M's can be shaken. 7) 128 small cards or buttons that may be cut from cardboard or construction paper, preferably with a different color on opposite sides, each marked with "U-235" all on one colored side and "Pb-207" on the opposite side that has some contrasting color.