Promoting learning through assessment
Mountaintop Fossil: A Puzzling
Phenomenon
By Page Keeley
E
lementary students encounter
a variety of Earth processes
that occur over the long time
intervals of geologic eras, periods,
and epochs. For example, the formation of the Grand Canyon, the uplift
of mountains, and the changed position of the continents happened over
time periods much longer than can
be observed in the classroom (or in a
lifetime). Once we move beyond stu-
dents’ experience of seconds, minutes, hours, days, weeks, and years,
the concept of thousands, millions,
and billions of years are almost incomprehensible (Trend 1998).
Some of these events and processes in Earth’s long geologic history present puzzling phenomena to
students. For example, on the peak
of Mount Everest, Earth’s highest
mountain, one can find fossilized
shells and traces of marine organisms. How does a clam shell, which
was once in the ocean, end up on the
top of a mountain? “Mountaintop
Fossil” (Figure 1) is a formative
assessment probe designed to elicit
students’ ideas about this phenomenon and uncover whether they can
use ideas about changes to Earth’s
surface over time and fossils found
in sedimentary rock layers to ex-
TABLE 1.
Fifth-grade students’ reasoning for “Mountaintop Fossil.”
Answer
Choice
Mrs. Esposito
Mr. Esposito
Rosa
Sofia
24
Grouped Similar Responses
Number
of
Students
Some birds fly high and drop things. A bird dropped the clam, which then turned
into a fossil.
3
Oceans don’t go up to mountaintops.
1
There was a large flood once.
3
Glaciers take a long time to carry rocks and fossils.
1
The land was under ocean before it rose up to form a mountain.
3
The ocean disappeared and a mountain grew over time.
2
There are mountains under the ocean. When the ocean dried up, the mountain
was left.
3
All mountains were once volcanoes. The shell got trapped in the volcano.
2
Fossils come out of volcanoes because of earthquakes.
1
Science and Children
plain the discovery of fossils on top
of a tall mountain (Keeley, Eberle,
and Tugel 2007).
The Next Generation Science
Standards’ grades 3–5 disciplinary core idea ESS1.C states, “Local, regional, and global patterns of
rock formations reveal changes over
time due to Earth forces, such as
earthquakes. The presence and location of certain fossil types indicate
the order in which rock layers were
formed” (NGSS Lead States 2013).
This disciplinary core idea indicates
that students should learn that fossils can be used as evidence that the
surface of the Earth has changed
over time. Fifth-grade responses
to this probe uncover several ways
of thinking about the puzzling discovery of a marine fossil on top of a
mountain. Table 1 shows a profile of
a fifth-grade class that organizes students’ thinking into commonly held
ideas for each selected response.
Students who chose Mrs. Esposito’s response show no evidence
of understanding that Earth’s surface has changed over time. They
may think mountains have always
existed where they are, which mirrors geoscience-education research
findings that show students of all
ages may think that the Earth has
always been the way it is now and
that any changes are sudden and
comprehensive. Students who chose
Mr. Esposito’s response recognize
that wind, water, and ice change the
land but erroneously apply that idea
to the mountaintop-fossil phenomenon. Three of the students polled for
Table 1 think a catastrophic event
(a great flood) carried the fossils to
the mountaintop. Another student
recognizes that glaciers cause a
FIGURE 1.
Mountaintop Fossil probe.
long-term erosion process but does
not account for the mountain. Rosa
has the best answer. Some students
who chose Rosa reveal partially developed knowledge about how land
that was once covered by ocean
can eventually become mountains
through some type of “uplifting”
process. Another student thinks the
mountain always existed but was
once underwater. Students who selected Sofia’s response have ideas
similar to Phillips’s (1991) findings,
which show that many students believe that mountain-building occurs
only through catastrophic events
such as earthquakes or volcanoes. In
all of the responses, there was no indication that students thought about
how the fossil formed and how we
use rock layers that contain fossils to
understand how the landscape has
changed over long periods of time.
As with all formative assessment
probes, the teacher will use students’ ideas to plan instruction that
will help them understand how fossils form and will provide evidence
of changes to Earth’s landforms,
bodies of water, and the types of organisms that live in an area. Planned
instruction can also show students
how forces such as the “pushing up”
of Earth’s surface over long periods
of time can form mountains (details about uplift and plate tectonics are further developed in middle
school). These two ideas are con-
December 2015
25
nected to understand the puzzling
mountaintop-fossil phenomenon.
Carefully planned instruction will
help students give up their idea that
Earth has not changed over time and
accept the explanation that some
changes happen over long time
scales. The next step may be to uncover students’ ideas about different
layers of rock with different types of
fossils. What do these layers reveal
about changes to the Earth?
Earth is a puzzle, and the use of
formative assessment can help teachers and students put pieces of that
puzzle together. ■
Page Keeley (pagekeeley@gmail.
com) is the author of the Uncovering Student Ideas in Science series
(http://uncoveringstudentideas.
org) and a former NSTA President.
References
Keeley, P., F. Eberle, and J. Tugel. 2007.
Uncovering student ideas in science:
25 more formative assessment
probes. Arlington, VA: NSTA Press.
NGSS Lead States. 2013. Next
Generation Science Standards: For
states, by states. Washington, DC:
National Academies Press. www.
nextgenscience.org/next-generationscience-standards.
Phillips, W. 1991. Earth science
misconceptions. The Science Teacher
58 (2): 21–23.
Trend, R. 1998. An investigation into
understanding of geological time
among 10- and 11-year-old children.
International Journal of Science
Education 20 (8): 973–988.
NSTA Connection
Visit www.nsta.org/SC1512 for
the “Mountaintop Fossil” probe.
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