An inquiry-based lesson on
geologic principles
S
Ronald S. Hermann and Rommel J. Miranda
cience is full of rich vocabulary. But the same terms that provide explanatory power to the discipline can also be a barrier to students’
understanding of scientific concepts. Crowther et al. (2011) present
a three-tiered classification system in which basic familiar words are
the first tier, high-frequency words used in academic settings (e.g., observe and
investigate) are the second tier, and low-frequency, domain-specific words (e.g.,
isotope and photosynthesis) are the third.
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F i g u re 2
Which layer of the sandwich came first?
Was the cheese made before the
pepper fragments were added?
Science teachers are responsible for helping students
understand and articulate third-tier science vocabulary. One
way to do this is to explain the definitions of new scientific
terms before teaching content. But explaining scientific terms
before exploring what they mean makes inquiry-based instruction more difficult.
This article describes an approach in which students develop and apply definitions prior to their formal introduction
to new vocabulary. We illustrate this approach with a lesson
we’ve used with high school Earth science students on the
principles of stratigraphy, though the lesson can be modified
for other science classes as well.
T h e le s s o n
We present this 60-minute lesson in 5E format—Engage,
Explore, Explain, Elaborate, and Evaluate (Bybee 1997).
Many students—especially those whose first language is not
English—learn new vocabulary better using a graphical organizer. For example, the Frayer model (Frayer, Frederick,
and Klausmeier 1969), a useful aid to this activity, includes
four squares in which students write the definition, the
characteristics of the word, examples, and non-examples.
E n gage
The lesson begins with an inquiry question and a picture
projected on a screen. The question is: “How can we determine the order in which past events have occurred?”
The picture is of a cut sandwich with a toothpick extending from each half (Figure 1). Students are told they will
discover some fundamental principles of sandwich making
and apply those principles to their study of geology.
While students observe the picture, we ask if
they’ve ever seen this particular sandwich before. They
answer “no.” We then ask how the sandwich was
made. Students typically say that a slice of bread was
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Ronald S. Hermann
Ronald S. Hermann
F i g u re 1
placed on a plate, then piled with cheese followed by ham, bacon, tomatoes, lettuce, more
cheese, and finally, another slice of bread on
top. How could they know this? A typical
response is that they’ve made similar sandwiches this way before. We paraphrase
the students’ summarizing statements on
the board as: “The events that occurred
in the past are the same events that occur
today,” and elaborate on this idea. Students
copy the phrase in their notebooks and
are told they will look more closely at
the sandwich to better understand how
it was put together.
We then ask students which layer
of the sandwich was likely the first—
or oldest. If a student says the bread
was first, we ask if he or she means the
top or bottom slice. Students generally
agree that the bottom slice was the
first layer. How do they know?
Due to common sense, students
say, and they cite prior experience as evidence.
To clarify, we point to a stack
of books and ask whether the
book on the bottom was
likely placed there
first. Students typically respond “yes,”
The Stratigraphic Sandwich
F i g u re 3
Stratigraphic layer worksheet used during the Elaborate phase of the lesson.
Referring to the diagram, circle the letter of the layer, event, or object listed in pairs below that is older. On the
line, write the principle of stratigraphy you used to determine which is older.
1. Layer X or Event S___________________________
2. Object Z or Layer X__________________________
3. Layer A or Layer L___________________________
4. Event H or Event S__________________________
5. Object B or Object Z________________________
6. Layer N or Event H__________________________
7. Event S or Layer L___________________________
8. List the order of labeled layers, events, and objects from
the very oldest to the very youngest. Include every layer,
event, or object labeled with a letter.
Answer Key
1. Layer X. Principle of Crosscutting Relationships
2. Object Z. Principle of Included Fragments
3. Layer L. Principle of Superposition
4. Event H. Principle of Crosscutting Relationships
5. Object Z. Principle of Superposition
6. Layer N. Principle of Crosscutting Relationships
7. Layer L. Principle of Crosscutting Relationships
8. One possible order is, from oldest to youngest: O, F, L, Z, X, N, H, S, A, B, T, R. Students could argue that igneous
intrusion H and fault S occurred more recently as it is difficult to say for certain based on the evidence available,
though it is certain that intrusion H occurred before fault S.
and, say, therefore, the bottom book is older. We write
this principle on the board as: “Layers or other objects on
the bottom are older than those found above them.”
We then turn to the toothpick in the sandwich. Was the
sandwich made first and then the toothpick stuck in? Or
was each layer of sandwich added to an existing toothpick
one by one? Students respond that the sandwich must be
assembled before the toothpick is pushed through.
We then ask the class to imagine seeing two students
each with half of the sandwich on their desks. Would
they assume each student brought their half sandwich
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61
from home or that they cut a sandwich in class? Students
respond that a sandwich was cut in class, noting that the
layers in the two halves are identical and match up perfectly.
We restate this justification by saying that the sandwich must
be assembled before it’s cut through, whether by a knife or
toothpick. We then write on the board: “When layers are cut
through by another object, the cut is younger than that which
it cuts through.”
Finally, students are asked to think about how pepper jack
cheese (Figure 2, p. 60) was made. Was the cheese made first
and the pieces of pepper added later? Or were the peppers
cut up and mixed with the other ingredients as the cheese
was made? Students choose the second option. We write on
the board: “When one object is embedded within another,
the embedded object is older.”
E x p l o re
Next, students explore how the above
ideas can be applied to geologic settings.
We show them a series of pictures and
ask them to explain which layer or
event is older. Students work in pairs
to discuss how each picture relates to
the ideas they learned in the Engage
phase. Use a search engine to find images for this activity that show:
uu
uu
uu
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layers of rock (students often
say the lower layers are most
likely older than higher
ones)
a fault cutting through stratigraphic layers of rock (the fault
is deemed younger than the
layers it cuts through)
an igneous intrusion (also younger than the layers it cuts through)
fossil remains (explain that the
fossil is older than the rock layers it’s found within)
Explain
After students have applied the
principles of stratigraphy to geological settings, we call their attention to the statements written on the board. The class
discusses the fact that using long statements such
as these is cumbersome,
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and one way to simplify these ideas is to assign a word or
words to each. As a result, students come to realize that a
vocabulary word is sometimes needed to communicate an
idea efficiently.
We then ask students to read the related section on geologic time in their course textbook. As they read, they work
with a partner to identify the vocabulary terms that match
the concepts developed earlier in the lesson. Students are then
called to the board to write the vocabulary term next to the
appropriate statement.
For example, students write principle of uniformitarianism
next to the statement that “The events that occurred in the
past are the same as those that occur today.” We encourage
students to look for other words they know that make up the
word uniformitarianism, such as uniform, and relate them to
the definition. We then ask them to think about examples of
geologic processes that occurred in the past
and still occur today and to provide evidence of their occurrence. Some students
give the example of watching lava cool
to form igneous rock and hypothesize
that if similar igneous rocks are
found to be millions of years old,
they likely formed from lava that
cooled millions of years ago.
Next to the statement, “Layers
or other objects on the bottom are
older than those found above them,”
students write the term principle of
superposition, identify the words
super and position, and discuss how
they relate to the definition.
Next to the sentence, “When layers are cut through by another
object, the cut is younger than
that which it cuts through,”
students write principle of
crosscutting relationships. They
once again look for ways to relate
this to the words they already
understand—looking for contextual
clues to help them remember the vocabulary word.
Finally, students write principle of
included fragments next to the line,
“When one object is embedded
within another, the embedded
object is older.” Students
are familiar with the words
included and fragments and
discuss how they relate to the
statement written on the board.
The Stratigraphic Sandwich
They then write the definition found in their textbook in
their science notebooks for each word presented and compare
it to the classroom definition.
E l a b o rat e
With the vocabulary words conceptualized, students are
challenged to apply the vocabulary. Each student receives
a cross-sectional stratigraphic layer for an area containing several rock layers with faults, igneous intrusions, and
embedded fossils (Figure 3, p. 61). They answer a series
of written questions comparing two labeled layers, events,
or fossils, and circle the one that is older. They then state
which principle they applied to answer these questions.
Finally, they rank all the labeled layers, events, and fossils from oldest to youngest. Students or student groups
present their solutions, or evidence-based arguments, and
discuss them as a class.
E va l u at i o n
To understand the extent to which students can apply the
principles and describe how they’re used, they complete
two evaluation components. First, we provide them with a
piece of paper on which to develop their own cross-sectional stratigraphic columns, which include a series of layers,
faults, intrusions, and fossils—each of which they randomly
label with a letter. The drawing should only be solvable in
one way, such that each event is distinctly older or younger
than the other events. Students then switch their papers with
a classmate, who will either rank the labeled items from oldest to youngest, or state why it is not possible to do so.
Next, the peer returns the paper to the student who produced it. The two students then discuss their understandings
of the concepts and how they relate to the cross-sectional
stratigraphic column. We address any inconsistencies or
disagreements with teacher input and occasional whole-class
discussions about specific issues that will benefit all students
as they come to better understand the concepts.
Students then write a short essay describing the manner in which the principles of stratigraphy can be used to
determine the ages of rock layers, faults, fossils, and intrusions. Students submit this response for a grade. We provide
written feedback about how accurately the student response
describes how the principles are used to better understand
the relative ages of layers, events, and fossils within a stratigraphic column.
Co n c l u s i o n
Students must develop a strong command of scientific
terminology to deeply understand science and to clearly articulate science concepts. Much of the previous literature on learning scientific vocabulary has focused on
written text (Young 2005), English as a second language
(Glen and Dotger 2009), students
with learning disabilities (Shook,
Hazelkorn, and Lozano 2011), and
elementary-level students (Leung Keywords: Geology
2008). The method outlined in this at www.scilinks.org
article differs in that it’s intended to Enter code: TST041301
be implemented orally and visually—
rather than through written text—and is appropriate for all
students new to unfamiliar vocabulary words. Moreover, it
provides a way to incorporate inquiry instruction while introducing new vocabulary, especially with students who are
learning English as a second language.
In high school science classrooms, it’s not uncommon to
have students define vocabulary words prior to a lesson, with
the aim of better understanding concepts they’ll more fully
develop later. Though this approach is valid, it’s not consistent
with inquiry-based science instruction. The lesson on relative
dating described in this article demonstrates one way that
vocabulary can be introduced in a lesson—by developing a
definition as a class, applying the definition to new scenarios,
and then assigning the scientific vocabulary word to the definition. Through this process, students explore the ideas prior
to formal explanation—which is in line with inquiry-based
science instruction and can enhance science learning for all. n
Ronald S. Hermann ([email protected]) and Rommel J.
Miranda ([email protected]) are assistant professors of
science education at Towson University in Towson, Maryland.
References
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