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ConcepTest: Oldest Rocks

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


Carefully examine the relative positions of the lettered arrows on the timeline below and estimate the ages represented by each arrow. Identify which letter corresponds most closely to the age of the oldest known rock on Earth.

a. C
b. D
c. E
d. F
e. G

Student Responses:

The correct response is C.
Percentage of students choosing this answer. (% Before Discussion/% After Discussion):

a. C(3%/0%)
b. D (13%/0%)
c. E (40%/73%)
d. F(24%/20%)
e. G (20%/7%)

in a small (< 60 students) environmental geology class

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:


Geoscience:Geology:Historical Geology

Resource Type

Activities:Classroom Activity:Short Activity:ConcepTests

Grade Level

College Lower (13-14):Introductory Level

Ready for Use

Ready to Use

Earth System Topics

Time/Earth History


Time/Earth History


Teach the Earth:Teaching Environments:Intro Geoscience