Gizmo of the Week: Half-life

Radiocarbon dating has revolutionized archeology and paleontology by providing a way to precisely date ancient organic materials such as bones, scraps of cloth, or ashes from a fire pit. Radiocarbon dating depends on the slow but steady decay of radioactive carbon-14 atoms. This process is modeled in the Half-life Gizmo.

In the Half-life Gizmo, students explore radioactive decay in a safe environment, observing and graphing the decay of a hypothetical short half-life material. The graph shows both the actual decay curve for the atoms shown and the theoretical curve for a large sample. Based on the graph, students then estimate the half-life of the material. The lesson concludes with an application of radiocarbon dating based on the principles demonstrated by the Gizmo.

Recently, radiometric dating using uranium has been used to date mastodon bones in California that may have been butchered by early humans. If the dates prove to be correct, this could represent evidence of humans in North America over 100,000 years earlier than humans were previously believed to be here! The finding is very new and fiercely disputed, so stay tuned!