ConcepTest: Oldest Rock Dating #1

ConcepTest questions by David McConnell , David Steer , Walter Borowski, Jeffrey Dick, Annabelle Foos, Jeffrey Knott, Alvin Konigsberg, Michelle Malone, Heidi McGrew, Kathie Owens, and Stephen Van Horn

Created with funding from NSF CCLI Award #0087894.
This material was originally created for Starting Point:Introductory Geology
and is replicated here as part of the SERC Pedagogic Service.


The world's oldest known rock is approximately 4 billion (4,000 million) years old. What are the approximate relative percentages of parent and daughter isotopes for Uranium-238 and Lead-206 (half-life = 4.5 billion years)?

a. 75% parent & 25% daughter
b. 45% parent & 55% daughter
c. 55% parent & 45% daughter
d. 25% parent & 75% daughter

Student Responses:

No data yet. The correct response is d.

If you would like to help acquire more Before and After statistics for this example, please contact the authors (see link at top of page).

References and Notes:

The use of ConcepTests and Peer Instruction is discussed in detail on the ConcepTest page.

McConnell, D.A., Steer, D.N. and Owens, K.A., 2003, Assessment and Active Learning Strategies for Introductory Geology Courses, Journal of Geoscience Education, 51(2), 205-216.

McConnell, D.A., Steer et al., 2006, Using Conceptests to Assess and Improve Student Conceptual Understanding in Introductory Courses, Journal of Geoscience Education, (54(1), 61-68.