They then gather the radioactive, or M side up M&Ms, put them back in the container, and then pour them out again. and continue this process until all M&Ms are stable, or M side down.
Paul, MN, based on an original activity retrieved from also with the help of Jenni Johansen (other 8th grade science teacher at So. Paul Junior High School In this activity, students gain a better understanding of radioactive dating and half-lives.
C14 is continually being created and decaying, leading to an equilibrium state in the atmosphere.
When the carbon dioxide, containing C14 as well as stable C12 and C13, is taken in by plants it is no longer exposed to the intense cosmic ray bombardment in the upper atmosphere, so the carbon 14 isotope decays without being replenished.
Daughter isotopes are represented by the M side down (stable).
Students begin by pouring the 100 M&Ms on the table, and set aside the "stable" isotopes (M side down).