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Ab s t r A c t
A standard part of biology curricula is a project-based assessment of cell structure
and function. However, these are often individual assignments that promote little
problem-solving or group learning and avoid the subject of organelle chemical
interactions. I evaluate a model-based cell project designed to foster group and indi-
vidual guided inquiry, and review how the project stimulates problem-solving at a
cellular system level. Students begin with four organism cell types, label organelles,
describe their structures, and affix chemicals produced or needed for each organ-
elle’s function. Students simulate cell signaling, cell recognition, and transport of
molecules through membranes. After describing the project, I present measures of
student participation and a rubric, compare individual versus group work, and
highlight future modifications, including alignment with the Next Generation
Science Standard of “Structure, Function, and Information Processing.”
Key Words: Biology; guided inquiry; cell model; group and tactile learning;
organelles.
Project History
In fall 2008, I introduced a cell-modeling project in a middle school
science magnet curriculum. As I used it, I sought ways to increase
learning and guided inquiry through group and individual discussion
and participation and through tactile work.
However, to discover the merit in these changes,
they had to be tested in the classroom.
The project described here, “A Cellular
Encounter,” is titled to avoid confusion and
comparisons between it and other cell projects.
Topics include cell signaling, membrane perme-
ability, chemical reactions and the organelles in
which they occur, and a culminating question
comparing the study of the cell to life itself.
Responding to student feedback, peer
review of the project with experts, reviews
with teaching colleagues, and insight gained from presenting it
publicly (see Acknowledgments), I made further changes for 2013,
keeping in mind the Next Generation Science Standards (NGSS; NGSS
Lead States, 2013). For example, the standard for Cell Structure and
Function (MS-LS1-2) states the need “to develop and use a model
describing functions of a cell as a whole, and ways parts of cells con-
tribute to functions. Emphasis is on the cell functioning as a whole
system and the primary role of identified parts of the cell, specifi-
cally the nucleus, chloroplasts, mitochondria, cell membrane, and
cell wall.”
Here, I report on recent modifications, observations, results,
and evolution of the project. I also cover learning approaches, par-
ticipation, student roles and performance, methods of individual and
group assessment, and grading rubrics.
Alternatives for Constructing Cell
Models & Projects
Depending on the grade one teaches, either a basic or a more advanced
lesson describing the structure and function of the cell is required.
Many of these lessons include viewing various cells under the micro-
scope and an individual cell project. When I first taught the project,
students made a model cell, either plant or animal, from Styrofoam.
Once the model was constructed, students labeled cell parts and
organelles (an example is at http://niki319
.blogspot.com/2008/02/cell-model.html).
Another option is to explore cell structure
and function through a web quest; one such
quest is called “Celebrate Cells” (http://www
.can-do.com/uci/ssi2001/cells.html). A dif-
ferent approach involves making a “cell city” to
explain the functions of organelles and the cell
(Grady & Jeanpierre, 2011).
Undergraduate options include a group
project in which students select a disease and
then explain how it affects the cell and its
organelles. For this teacher, project-based cell biology moved stu-
dents away from a content-only curriculum to one equally focused on
The American Biology Teacher, Vol. 76, No. 8, pages 544–549. ISSN 0002-7685, electronic ISSN 1938-4211. ©2014 by National Association of Biology Teachers. All rights reserved.
Request permission to photocopy or reproduce article content at the University of California Press’s Rights and Permissions Web site at www.ucpressjournals.com/reprintinfo.asp.
DOI: 10.1525/abt.2014.76.8.8
544 THE AMERICAN BIOLOGY TEACHER VOLUME 76, NO. 8, OCTOBER 2014
Depending on the grade
one teaches, either a basic
or a more advanced lesson
describing the structure
and function of the cell
is required.
Joel I. Cohen
InquIry & “A Cellular Encounter”:
InvestIgatIon Constructing the Cell as a
Whole System Using Illustrative
Models
ReCoMMenDATIon
“communication, leadership, teamwork,” and other skills useful over
their lifetime (Wright & Boggs, 2002). It contains detailed rubrics
for the cell and organelle’s structure and function, and, in this case,
what happens to these entities when hit by disease.
Project Design
Four objectives led to the current version of the “Cellular Encounter”
model. The first was an attempt to make the cell model, and its design
process, more dynamic than the fixed or static versions summarized
above. Guided inquiry, a form of active learning (Lee, 2010), was
introduced as a means for each student group to design, draft, and
place compounds and membrane details on the scale model.
With this approach, the final product was based on a “shared
process within the classroom community” (Khourey-Bowers, 2011).
The large-scale model of the cell let a group of students comfort-
ably decide where to place chemical compounds, how to direct them
toward the correct organelle, and how best to organize their flow
through the membrane.
The second objective was for students to understand the cell as a
whole, coordinated system, with all organelles supporting the basic
characteristics of life (see NGSS Lead States, 2013). Through this
model, students are able to see how the reactants and products used
in organelle chemical reactions interrelate instead of studying organ-
elles in isolation and as unconnected to each other, and how they
serve the needs of the cell.
The third objective was to reinforce prior learning of the funda-
mental characteristics of life and chemical reactions that occur in a
cell. In our science curriculum, the “Cellular Encounter” model comes
after the study of chemical reactions, elements, and compounds.
Here, students focus on five major elements of life (carbon, hydrogen,
nitrogen, oxygen, and iron).
However, if cell science were taught from both curricular plans
and the organization of the textbook, students would not have been
asked to relate their now prior knowledge of chemical reactions
with the actual sites of chemical processes in the cell. In “A Cellular
Encounter,” chemical reactions are seen as part of the cell’s “factory,”
capable of making ~20,000 compounds.
Consequently, tables found in the student packets reinforced
student knowledge of specific chemicals of life needed or produced
by the cell. For example, in the initial table, students are asked to
determine the roles of carbohydrates, lipids, proteins, nucleotides,
nucleic acids, and water and how cell organelles use them. The
compounds just listed are then used in Table 1; the third column is
left blank because student groups must determine the organelle(s)
housing the respective chemical reaction.
In our curriculum, “A Cellular Encounter” reinforces and coin-
cides with the introduction of the microscope to study asexually
reproducing organisms, such as hydra and yeast (budding), bacteria
and amoeba (fission), planaria (regeneration), and strawberry
( vegetative propagation). To ensure that microscopic images were
not an isolated experience, special attention was given to the use of
specific organisms (Greene, 2005). This occurred by having students
design and draft their models using organisms we have studied, not
generic cell types.
The fourth objective was to stimulate individual ownership and
participation with rubrics and information that facilitated students
finding their own answers, rather than constantly and automatically
deferring to the teacher. The specificity of tangible requirements
combined with the need for additional communication supported
the project’s active learning (Khourey-Bowers, 2011).
Implementation
To implement the project, a suitable format for a scale-model cell
was needed. It had to provide ample room for interactive group
work, foster student-to-student learning, challenge advanced
learners, and be suitable for scaffolding for learners with special
needs. I experimented with various media, and tested alternatives in
other class settings. Eventually, I selected KELVIN DesignGrid Paper
(17 × 22 inches; http://www.kelvin.com/mm5/merchant.mvc?Store_
Code=k&Screen=PROD&Product_Code=420238), which provides a
“drafting” approach while having a designated area for student, name
of cell, and teacher approval. The graphing format of the DesignGrid
paper (as shown at the product website) gave the students a sense
of order and layout that preempted poor planning. However, large
graph paper or posterboard could be substituted.
Students deciphered structures and functions of a particular
organism’s cell to determine the specific cell assigned to each group
(Table 2). Four organisms were selected and divided evenly over eight
table groups. Presently, I use cell types from the following organisms
for the project’s model: strawberry plant, salmonella bacteria, human
cells, and hydra.
In Table 2, the teacher circles specific properties ahead of class
that serve as clues about which of an organism’s cells a particular
table group will study. This method of determining the organism’s
cell, rather than being told from the outset, fosters guided inquiry,
group decision-making, and participation. It reinforces knowledge of
THE AMERICAN BIOLOGY TEACHER CONSTRUCTING THE CELL 545
Table 1. Organelle compounds and their synthesis.
Your Cell Needs:
Compounds Needed for Cellular
Chemical Reactions
Name the Organelle(s) Where the
Compound Is Used or Made
1. Protein Amino acids
2. Solar-derived glucose molecules Solar energy; H2O; CO2
3. DNA Nucleotide molecules
4. Grow cell wall Cellulose molecules
5. Repair cell membrane Lipids + proteins
6. Energy from food Glucose + oxygen
7. Waste removal Enzymes + wastes
each cell’s properties by using prior knowledge, notes, textbooks, and
group decision making. For this reason, group scores and participa-
tion were allocated, even though some school districts are moving
away from this type of grading.
Once the organism and cell type were agreed upon by each
member, the group sought out their “matching” cell type among
the other table groups of four students each. This required students
to walk from one table to the next, comparing results from their
cellular clues, until the matching cell was found. These matching-
cell-type tables then had to communicate with one another to
obtain chemical compounds needed by organelles. This ensured
that each group of students was up and communicating with its
matching cell.
The next step was experimenting on how best to draw the cell
and its membrane while allowing for the passage of compounds.
Membrane permeability and chemical exchange required spe-
cial attention to make them tangible to students. Even though the
membrane was described as a “gatekeeper” or, more specifically, a
fluid mosaic structure, what this means chemically and how such
things work remained a mystery for many learners. Therefore,
I asked that they construct “channels” for molecular exchanges in
their models.
Students visualized channels in the membrane by erasing four
small areas of the membrane drawn in pencil. By erasing these bits
of the membrane, they could see how channels permeate the mem-
brane and how chemical compounds and waste can be exchanged.
This way, by the time students enter high school, they are familiar
with the permeability of membranes, what type of compounds pass
through it, and how it serves as a gatekeeper. While not explaining
the details of protein channels and transport proteins that they learn
in high school, this model provides the first step in preparation for
later AP Biology studies (see College Board, 2011).
In subsequent modifications, membrane permeability will stress
that water enters through channels, whereas carbon dioxide, oxygen,
and lipids diffuse directly through the membranes. Sugars, amino
acids, nucleotides, and proteins will use other transport mechanisms,
as appropriate for seventh grade.
The structure and function of key organelles were reinforced
by the project, as were connections between cellular processes and
their functions in a whole cell system. For this reason, the drawing
had to be large enough to accommodate eight organelles, to affix
appropriate compounds to the organelles, or to depict compounds
entering the cell through the membrane.
For each cell model, compounds were lined up to enter or leave
the cell, or to be used by particular organelles. This exchange was
accomplished by table groups working with their “cellular” partner
table. Because the compounds and other cellular needs came from
their matching cell, students got up and carried out the process of
cellular exchange and communication to obtain and use required
compounds.
The molecules or compounds included in the project were sugar,
protein, amino acid, oxygen, lipids, water, carbon dioxide, and
nucleotides. These compounds were included to reinforce prior les-
sons on chemical reactions that were now related to the organelles
in which they take place. Waste is included in the model as it is
removed from the cell by the lysosomes and made ready by intracel-
lular digestion to be released back into the cell in the form of vesicles.
Sunlight is included for the chloroplast and enzymes as necessary for
many reactions.
Symbols were compiled representing each compound listed
above. Students obtained compounds from their matching cell table,
cut these out, determined where they entered the membrane, and
affixed some of these compounds to organelles for chemical reactions.
For example, four symbols for amino acids were cut out, with two
flowing through the membrane and two others placed on the ribo-
some, where they were used to build proteins (see Figure 1).
To demonstrate cell-to-cell communication, recognition, and
signaling, students matched unique cell-surface receptor sites with
the correct signal molecule. The paper cutouts for the receptors came
from one table, but the matching signal molecules had to come from
546 THE AMERICAN BIOLOGY TEACHER VOLUME 76, NO. 8, OCTOBER 2014
Table 2. Basic properties of specific organisms and their cells used in determining which of four possible
organisms belong to a given table group.
Unicellular Multicellular
Prokaryote Eukaryote
Heterotroph Autotroph
Cells are organized; stick
together in the right place
Cells are individual or don’t
“stick together”
Primary form of reproduction Asexual Sexual Both
Cell/nuclear division: Mitosis Meiosis for sexual reproduction Both
Organelles and DNA:
Nucleus
Present Absent
Cell wall
Present Absent
Chloroplast
Present Absent
Mitochondrion
Present Absent
DNA
On chromosomes, inside a
nucleus
On chromosomes inside the cell
itself, lacking a nucleus
the cell’s companion table, indicating that the students had “acted
out” cell communication. Each table group’s scale model had to have
four sites, with the correct signal placed on them. Once applied,
these were easily seen and graded to ensure that “cell communica-
tion” occurred.
Assessment Tools
“A Cellular Encounter” became the culminating project for our unit
on cells, requiring three full 90-minute classes. Grading of the project
was based on the following assessment tools:
a group score for the final scale model drawing using a project 1.
rubric
an individual grade for the project packet, and 2.
a grade provided by the teacher for observations of group deci-3.
sion making and individual participation.
Grading Rubric
The rubric used to grade student knowledge, performance, and
the accuracy of the model is shown in Table 3. The total score for
this part of the assessment is 50 points. The second 50 points come
from individual responses to the final, open-ended questions, with
points awarded for use of evidence in the answer and completeness
of response.
An example of one version of the animal cell model is presented
in Figure 1. The range of organelles selected is clear, as are the chan-
nels through the membrane. Requisite compound symbols are
attached to each organelle or in transit through the membrane. As
noted above, further specificity can be added to capture exactly what
type of mechanism is used by each specific compound to enter or
leave the cell.
As for the nucleus, symbols for nucleic acid molecules were
correctly located; however, no further activity with the nucleus
was planned for this version of the model. These nucleic acids can
be seen attached to the nucleus of the animal cell. This cell model
also notes the ATP production occurring from the mitochondrion.
There is clearly a place where other symbols could be inserted in
the nucleus, such as mRNA molecules making their way to the
ribosomes, or DNA itself, and copies to show how and where it
is replicated. Although these extra symbols were not included,
students were familiar with the nucleus as the cell’s information
and control center and were thus able to consider how protein
synthesis might occur and how these proteins would be packaged
to leave the cell.
THE AMERICAN BIOLOGY TEACHER CONSTRUCTING THE CELL 547
Figure 1. Student-generated model for animal cells.
Analysis & Reflection of Student Work
The project was undertaken by 141 students in five periods. This
required 35 table groups with an average of four students per group.
I rated the groups on their participation, supportive work habits,
and whether or not one or two students were carrying out the work
of others.
Approximately 50% of the groups had a score of 5 for partici-
pation. The other groups, despite warnings and encouragement,
worked consistently with less-than-full participation or with full
participation only at limited times. Despite the other 50% working
at less-than-optimal participation, all cell drawings were completed
and turned in for grading.
Students were initially presented with two concluding essays.
The first asked, “What can cells tell us about life?” The second asked
the students to choose one particular organelle, describe its function
in a cell, and tell what would happen if the cell did not have this
particular organelle. The first question proved much harder to answer
than the second. The students had numerous queries, including what
is a good answer, what does the question mean, and where should
548 THE AMERICAN BIOLOGY TEACHER VOLUME 76, NO. 8, OCTOBER 2014
Table 3. Rubric for cell model completion, group understanding, and accuracy.
Guideline Directions
Student
Check-off
Completed
as directed
(5 points)
Completed
with details
lacking
(3 points)
Incomplete or
did not follow
directions
(0 points)
Total Score
(completed
by instructor)
1. Identification A Each student’s name
and group should be
on drawing, neatly and
clearly written
2. Identification B Name of organism, type
of cell (plant, yeast,
animal, bacteria), and
mode of reproduction
written clearly
3. Planning An overall plan for
drawing and labeling
should be evident for
three cells, each touching
the other
4. Eight Organelles Each organelle labeled
correctly and explanation
of what it does
5. Size Drawing takes up entire
paper
6. Cell protein
signal receptors
4 per cell, must match
“partner” cell drawing
7. Plasmodesmata
and/or other
pathways in
membrane
4 openings in membrane
for passage of needed
cellular molecules using
cut out shapes
8. Placement and
numbering of
cellular chemicals
Correctly numbered
molecules must be
placed within membrane
receptors, affixed to
correct organelle, or on
gap junctions
9. Group
participation
Each person helps group
tasks
Full group 2 or 3 only 1 or 2 only
10. Demonstrated
understanding
Understanding of the
cell, its communication,
and its chemical
processes
Complete
understanding
Some
understanding
Lack of
understanding
Overall TOTAL ____ /50
they look for answers. Because I had experienced these questions
before, a number of topics were included for them to consider:
Six characteristics of life•
Functions and properties of the particular cell type they studied•
How and why cells communicate with each other•
Use of facts and observations from the project as supporting •
evidence.
Unfortunately, many students just began listing these things without
ever addressing or coming back to the actual question. For many stu-
dents, my comment was that “they had not answered the question.”
Even though we studied how and why cells are the fundamental cor-
nerstone of life, for many students, answers to this question were not
able to provide an adequate parallel between cells and life.
Those who succeeded with the first essay question did so
by connecting many of the themes of cells and life that we had
studied or that were brought out in this project. For example, one
student wrote that
This communication/interaction is impor-
tant because these cells work together to
keep the organism alive and it is necessary
to help the cell and its organism complete
its everyday functions. If these cells did not
communicate or share with each other they
wouldn’t be able to function.
A second example states that
Cells tell us why we’re able to exist. All cells are
able to reproduce through mitosis and meiosis,
obtain and use energy, produce waste, grow
and develop, and respond to the environment.
This shows us that there are certain require-
ments for life to occur. Also, we know that cells
trade compounds such as amino acids and
communicate through chemical signals.
In the third year, I had each group draw their cell in draft before
moving to the final product. I provided sheets of paper for the draft
that were about half the size of the final paper. I asked for them to
have me sign off on the draft, and when completed, I handed out the
special drafting paper. Insisting on a “first draft” clarified misconcep-
tions that students faced while beginning their scale drawing.
Current & Future Modifications
New concluding questions were prepared for 2014 to stimulate
inquiry. This change came from reviewing use of such questions in
a crayfish dissection. By asking such questions, students were seen
to more actively engage with the project (Goldstein & Flynn, 2011).
One question was prepared in line with the NGSS Clarification
Statement for cell models. This open-ended response question was
“How might you explain the making of a protein, beginning with
the cell’s DNA, until it is ready for transfer through the membrane?”
A second question was added to strengthen skills in evidence-
based solutions: “What evidence can you present for the connection
between the organelle’s function and the cell’s function, and what
would happen if a cell did not have this organelle?” These two ques-
tions, coupled with the improved accuracy of the cell model itself,
combined to increase the rigor of the model and to enable analysis
guided by NGSS.
To further diversify the project, other cell types can be added that
are related to microscopic and cell lessons, such as HeLa cancer cells
or cells transformed through recombinant DNA technologies. Next,
to strengthen ownership when studying organelles, each student will
select one organelle from their cell drawing and write a description
of that organelle on a file card in the first person, describing what the
organelle does and how it helps the cell. These cards will be glued to
the drawing and used for oral presentations.
Students could also be asked to demonstrate cell reproduction
asexually, such as by budding, or cell division through mitosis. This
would permit duplication of genetic material and show how it sepa-
rates and cells divide, with format and rubric modified accordingly.
Final Note: Because the entire packet for the model was too lengthy
for this publication, please contact me (cohenji@comcast.net) if fur-
ther information, rubrics, or example assessments are needed.
Acknowledgments
I thank Professor Stephanie Wolniak at the University of Maryland for
time spent increasing the accuracy and content of the project. Other
changes took place following conversations during and after a pre-
sentation at the 2013 annual meeting of the Maryland Association
of Science Teachers. Thanks to the following individuals at Parkland
Magnet Middle School: Ms. M. Edwards-Ransom, who tested the
project along with me over the past few years and whose input and
experiences shaped many changes in the project’s design; Ms. Donna
Blaney, Magnet Coordinator, who observed and provided written com-
ments; and Ms. Jennifer Wingate, Science RT, for formal review obser-
vations of the project.
References
College Board. (2011). AP BIOLOGY Curriculum Framework 2012–2013. New York,
NY: College Board.
Goldstein, J. & Flynn, D.F.B. (2011). Integrating active learning & quantitative skills
into undergraduate introductory biology curricula. American Biology Teacher,
73, 454–461.
Grady, K. & Jeanpierre, B. (2011). Population 75 trillion – cells, organelles, and
their functions. Science Scope, January, 64–69.
Greene, H.W. (2005). Organisms in nature as a central focus for biology. Trends in
Ecology, 20, 23–27.
Khourey-Bowers, C. (2011). Active learning strategies: the top ten.
Science Teacher,
78,
38–42.
Lee, V.S. (2010). The power of inquiry as a way of learning. Innovative
Higher Education, 36, 149–160.
NGSS Lead States. (2013). Next Generation Science Standards: For States, By States.
Washington, DC: National Academies Press. http://www.nextgenscience.org/.
Rasmussen, C., Resler, A. & Rasmussen, A. (2008). Cell city web quest. Science
Scope, January, 12–14.
Wright, R. & Boggs, J. (2002). Learning cell biology as a team: a project-based
approach to upper-division cell biology. Cell Biology Education, 1, 145–153.
JOEL I. COHEN is a Science Teacher at Parkland Magnet Middle School for
Aerospace Technologies, Rockville, MD 20853. E-mail: cohenji@comcast.net.
THE AMERICAN BIOLOGY TEACHER CONSTRUCTING THE CELL 549
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