A lesson in which students analyze the chemical data that led researchers to conclude that the K-T boundary layer contained an extraordinary concentration of iridium.
Appropriate for: high school physics, chemistry, and earth science (all levels)
This lesson serves as an extension to the Howard Hughes Medical Institute short film The Day the Mesozoic Died. The film identifies the presence of high quantities of iridium (Ir) in the clay layer at the K-T boundary as a key piece of evidence of the asteroid impact hypothesis. In this lesson, students will calculate the chemical signatures of two K-T boundary samples and compare them to those of a chondrite—a rock that originated from space—and a typical basalt—a rock that originated from Earth’s mantle. Students then evaluate the data to determine how well the evidence supports the conclusion that the iridium signal in K-T sediments was produced by an extraterrestrial impact.
NGSS (April 2013)
HS-PS1.A, HS-ESS1.B, HS-ESS1.C, HS-ESS2-2, HS-ESS2.A
Common Core (2010)
CCSS.Mathematics.MP.4, CCSS.Mathematics.MP.2, CCSS.ELA-Literacy. RST.9-10.7, CCSS.ELA-Literacy. RST.11-12.7 CCSS.ELA-Literacy.WHST.9-12.1, CCSS.ELA-Literacy.WHST.9-12.2