-
Can Computer Animations Affect College Biology Students'
Conceptions about Diffusion &Osmosis?Author(s): Michael J.
Sanger, Dorothy M. Brecheisen, Brian M. HynekSource: The American
Biology Teacher, Vol. 63, No. 2 (Feb., 2001), pp. 104-109Published
by: University of California Press on behalf of the National
Association of Biology TeachersStable URL:
http://www.jstor.org/stable/4451051 .Accessed: 05/05/2011 00:02
Your use of the JSTOR archive indicates your acceptance of
JSTOR's Terms and Conditions of Use, available at
.http://www.jstor.org/page/info/about/policies/terms.jsp. JSTOR's
Terms and Conditions of Use provides, in part, that unlessyou have
obtained prior permission, you may not download an entire issue of
a journal or multiple copies of articles, and youmay use content in
the JSTOR archive only for your personal, non-commercial use.
Please contact the publisher regarding any further use of this
work. Publisher contact information may be obtained at
.http://www.jstor.org/action/showPublisher?publisherCode=ucal.
.
Each copy of any part of a JSTOR transmission must contain the
same copyright notice that appears on the screen or printedpage of
such transmission.
JSTOR is a not-for-profit service that helps scholars,
researchers, and students discover, use, and build upon a wide
range ofcontent in a trusted digital archive. We use information
technology and tools to increase productivity and facilitate new
formsof scholarship. For more information about JSTOR, please
contact [email protected].
University of California Press and National Association of
Biology Teachers are collaborating with JSTOR todigitize, preserve
and extend access to The American Biology Teacher.
http://www.jstor.org
-
Can Computer Animations Affect College Biology Smdents'
Conceptions About
Diffusion & Osmosis? Michael J. Sanger Dorothy M. Brecheisen
Brian M. Hynek
T HE concepts of diffusion and osmosis are very important for
biology students to understand. Diffusion is the primary method of
short-dis-
tance transport in cells and cellular systems. Osmosis is used
to explain water uptake by plants, turgor pressure in plants, water
balance in aquatic creatures, and transport in living organisms
(Odom 1995). Unfortunately, students find these topics very
difficult to understand (Friedler, Amir & Tamir 1987) and
several biology education researchers have reported student
misconceptions associated with these topics (Marek 1986; Zuckerman
1994; Odom & Barrow 1995). One reason why students may have
difficulty with the concepts of diffusion and osmosis is because
these concepts require students to visualize and think about
chemical processes at the molecular level (John- stone &
Mahmoud 1980; Friedler, Amir & Tamir 1987; Westbrook &
Marek 1991).
A decade ago, Nurrenbern and Pickering (1987) discovered that
students who are successful in solving numerical chemistry problems
did not necessarily understand the molecular concepts underlying
these problems. Since that time, others have documented students'
difficulties in answering visual conceptual questions based on the
particulate nature of matter (Gabel, Samuel & Hunn 1987; Sawrey
1990; Pickering 1990; Nakhleh 1993). Research in this area has
demon- strated that instruction involving computer anima- tions can
facilitate the development of students' visu- alization skills and
their abilities to think about chemi- cal processes at the
molecular level (Williamson & Abraham 1995; Russell et al.
1997; Sanger & Green- bowe 1997).
The purpose of this study was to determine whether viewing
computer animations depicting the molecular processes of diffusion
and osmosis would
affect students' conceptions of these topics. Students'
conceptions of diffusion and osmosis topics were measured using the
Diffusion and Osmosis Diagnostic Test (Odom 1995; Odom & Barrow
1995).
Methods This study was performed using 149 students
enrolled in a second-semester introductory college biology
course at a small Midwestern university. These students are
predominantly first-year biology majors who were also enrolled in a
second-semester introductory college chemistry course. All of these
students attended the same lecture section which met for three
hours per week and was taught by a college biology instructor who
has taught this class three times a year for 12 years. Each student
was also enrolled in one of six different laboratory sections
containing 21 to 28 students who were taught by a college biology
instructor or a graduate student.
This research study was performed in the labora- tory sections
after the students had received instruc- tion on diffusion and
osmosis in the lecture section. The laboratory sections were
randomly assigned to either the control or experimental group.
Students in the experimental group received instruction using two
computer animations to explain the molecular behaviors associated
with the processes of diffusion. Both groups performed several
experiments including the diffusion of potassium permanganate in
water, the osmosis of water and glucose (but not starch) through
cellulose dialysis tubing, and the effect on the cells of an Elodea
leaf after being placed in hypotonic, isotonic and hypertonic
solutions. The major difference between the two groups is that the
experimental group viewed two animations before performing these
experiments while the control group did not.
The first animation depicted the molecular pro- cesses occurring
when perfume particles diffuse through the air (Figure 1). The
perfume particles were represented as pink circles (since the
perfume molecules would be very complex) and air was repre- sented
as N2 and 02 molecules. As the animation
Michael J. Sanger is an Assistant Professor of Chemistry and
Science Education and Dorothy M. Brecheisen is an Instruc- tor of
Biology at the University of Northern Iowa, Cedar Falls, IA
50614-0423. Brian M. Hynek was an undergraduate earth science and
all sciences teaching major at the University of Northern Iowa and
is now a graduate student in Earth and Planetary Sciences at
Washington University, One Brookings Drive, St. Louis, MO
63130-4899.
104 THE AMERICAN BIOLOGY TEACHER, VOLUME 63, NO. 2, FEBRUARY
2001
-
U S
FS 0
Figure 1. Computer screen image of the diffusion of perfume
molecules (circles) in air.
proceeds, the perfume particles and the air molecules collide
with themselves and with each other until all of the particles are
evenly distributed throughout the screen. Students in the
experimental group viewed this animation three times while the
first author narrated the action appearing on the screen, empha-
sizing that the random motion and collisions of these particles
leads to this even distribution. This description of the movement
of perfume molecules in a room is simplistic and ignores other
mixing processes (such as convection currents). However, it does
correctly demonstrate that all gaseous molecules are in constant
motion and, in the absence of convec- tion currents or other
forces, these molecules will slowly mix via diffusion.
The second animation starts with a drawing of a thistle tube
experiment that the students had seen and discussed in lecture
(Zuckerman 1994, 1995). It starts with a thistle tube covered by a
semi-permeable membrane and filled with Karo? syrup that has been
placed in a beaker of water. As the process of osmosis occurs, the
Karo? syrup level in the thistle slowly
rises and eventually levels out. The animation also depicts the
molecular processes occurring in this experiment (Figure 2). The
semi-permeable membrane is represented as a dashed line that
separates the Karo? syrup solution on top from the water on bottom.
The syrup particles are represented as brown circles for simplicity
and the Karo? syrup solution contains both syrup particles and H20
molecules. The holes in the semi-permeable membrane were made large
enough for the water molecules to pass through but small enough so
that the sugar particles cannot pass through them.
Students in the experimental group viewed the molecular portion
of the second animation three times. The first time, the students
were simply directed to watch the animation. These students were
asked which particles could travel through the mem- brane and why
and in what direction these particles moved. In each section, the
students replied that water molecules could travel through the
barrier but the syrup particles could not due to size effects, and
that the water molecules traveled in both directions
DIFFUSION & OSMOSIS ANIMATION 105
-
\~~ -- N
Figure 2. Computer screen image of the osmosis of water
molecules through a semi-permeable membrane between pure water and
a syrup solution.
but more water molecules moved from the pure water into the
syrup solution. The students viewed the animation again, with half
of the class counting the number of water molecules entering the
syrup solution and the other half counting the number of water
molecules entering the water solution. The students reported that
there were nine water mole- cules entering the syrup solution
throughout the animation and four molecules entering the water
solution, predominantly at the end of the animation. The students
were then allowed to watch the anima- tion one more time.
After performing the laboratory experiments men- tioned above,
both sets of students were asked to respond to the Diffusion and
Osmosis Diagnostic Test (DODT). The DODT consists of 12 two-tier
multiple choice questions. The first-tier responses are based on
content questions, while the second-tier responses ask students to
explain their choices in the first tier. The responses in the
second tier are based on misconceptions identified by student
responses to these questions and student interviews.
To determine the effects of viewing the computer animations,
responses to the questions on the DODT were compared from students
who viewed the anima- tions and from those who did not.
Results & Discussion Odom (1995) reported a list of student
misconcep-
tions he identified using the DODT. The number and percentage of
the students choosing responses consistent with these
misconceptions were tabulated for the control and experimental
groups, and these numbers were checked for statistically
significant differences. Table 1 contains a list of misconceptions
for which we found significant differences.
The most striking difference is that students who viewed the
animations were less likely to choose responses suggesting that
particle motion stops after equilibrium is reached (Misconceptions
1 and 2). While 8% of the students in the control group believed
that dye and water molecules stop moving once they are mixed
because otherwise the container would be
106 THE AMERICAN BIOLOGY TEACHER, VOLUME 63, NO. 2, FEBRUARY
2001
-
Table 1. Number (percentage) of student responses consistent
with misconceptions measured by the Diffusion and Osmosis
Diagnostic Test.
Misconceptions Control a Experimentalb
1. When a drop of blue dye is placed in a container of clear
water, the dye molecules 6 (8) 0 (0) stop; otherwise the container
would be different shades of blue.
2. Particles move from high to low concentration because they
tend to move until the two 27 (36) 14 (19) areas are isotonic and
then the particles stop moving.
3.- When a drop of dye is placed in a container of clear water,
the dye molecules continue 2 (3) 10 (14) to move around because if
they stopped, they would settle to the bottom of the container.
4. As the difference in concentration increases between two
areas, the rate of diffusion 36 (47) 23 (32) increases because the
molecules want to spread out.
5. When sugar is added to water, after a very long time the
sugar will be more 2 (3) 8 (11) concentrated on the bottom of the
container because sugar dissolves poorly or not at all in
water.
aN = 76 students bN = 73 students
different shades of blue, none of the students who viewed the
animation chose this response (z = - 2.45, p = .014). Similarly,
more students in the control group believed that particles move
until they are isotonic and then stop moving than in the experimen-
tal group (36% versus 19%), z = -2.23 and p = .026. In general, it
appears that these animations were successful in helping students
understand the dynamic nature of equilibrium processes, which is a
common and persistent misconception exhibited by students in
chemistry classes as well (Gorodetsky & Gussarsky 1986).
Although the students who viewed the animations were less likely
to believe that the particles stop moving once they reach
equilibrium, they were more likely to exhibit a misconception about
why these particles do not stop moving (Misconception 3). While
only 3% of the students in the control group believed that dye and
water molecules keep moving once they are mixed because otherwise
they would settle to the bottom of the container, 14% of the
students in the experimental group chose this response (z = 2.49, p
= .013). It appears that although the anima- tions convinced
students that the particles do not stop moving once they reach
equilibrium, it was not completely effective at convincing them why
they don't stop moving (random motion).
On the other hand, students who viewed the anima- tions were
less likely to attribute molecular motions to anthropomorphic
"desires" of the molecules (Mis- conception 4). More students in
the control group believed that as the difference in concentration
increases between two areas, the rate of diffusion increases
because the molecules want to spread out than in the experimental
group (47% versus 32%), z = - 1.98 and p = .048. Both Zuckerman
(1994) and Odom and Barrow (1995) cited the importance of
understanding the concept of osmosis as the result of random
molecular motions, and claimed that stu-
dents agreeing with the statement above attribute these motions
not to random collisions but to the wants or desires of the
molecules.
Although the animations had a positive effect on students'
conceptions about the particulate nature and random motion of
matter, the animation appeared to convince students that sugar does
not dissolve in water (Misconception 5). While only 3% of the
students in the control group believed that sugar does not dissolve
well in water, 11% of the students who viewed the animations chose
this response (z = 2.05, p = .040). Discussions with students
revealed that they interpreted the brown circles surrounded with
water molecules in the second animation (Figure 2) as suggesting
that the sugar and water particles did not completely mix with each
other and that these sugar particles did not dissolve in water.
This diffi- culty stems from students trying to apply rules that
work at the macroscopic level, like "if you can see
Science Item Writers - The General Educational Development
Testing Service (GEDTS) is recruit- ing science teachers to prepare
brief passages in- cluding graphics and multiple-choice test items
for the new GED 2002 Series Science Test. The GED Tests measure the
major academic skills and know- ledge associated with a four year
high school pro- gram of study. Please send your name, address,
phone number, and resume to: David Kuhn, GEDTS, One Dupont Circle,
NW Suite 250, Washington, DC 20036-1163: (office) (202) 939-9494;
(E-mail) david [email protected]; (Fax) (202) 939-8578.
DIFFUSION & OSMOSIS ANIMATION 107
-
the particles, the compound has not dissolved in water," to
pictures at the molecular level (Sanger 1999).
Implications for the Classroom This study demonstrates that
students who viewed
computer animations depicting the molecular pro- cesses
occurring when perfume particles diffuse in air and when water
osmoses through a semi-permeable membrane developed more accurate
conceptions of these processes based on the particulate nature and
random motion of matter (Misconception 4). They also had a better
conceptual understanding of the dynamic processes occurring in
equilibria reactions (Misconcep- tions 1 and 2). For the past
decade or so, chemical education researchers have stressed the
importance of asking students to think about chemistry concepts at
the particulate level (Nurrenbern & Pickering 1987; Gabel,
Samuel & Hunn 1987; Sawrey 1990; Pickering 1990; Nakhleh 1993)
and the evidence suggests that when students receive chemistry
instruction including particulate drawings, they are better able to
answer conceptual questions that are based on the particulate
nature of matter (Williamson & Abraham 1995; Rus- sell et al.
1997; Sanger & Greenbowe 1997). These results suggest that
instruction including computer
animations at the particulate level can help students understand
chemistry and biology concepts involving molecular processes. Some
of these biology concepts include Brownian motion, diffusion,
osmosis, 3D structure of DNA, cellular transport mechanisms
(membrane structure, passive and active transport, etc.), and
enzyme-substrate complexes.
Many newer versions of college biology textbooks are packaged
with a CD-ROM containing instruc- tional resources, including
computer animations of molecular processes (Krogh 2000; Raven &
Johnson 1999). High school biology textbooks, on the other hand,
tend to come with many ancillary materials for the instructor such
as CD-ROMs, videotapes, laserdiscs, or web site addresses, and
these materials also contain computer animations of biology
concepts at the particulate level (Miller & Levine 1998;
Strauss & Lisowski 1998). Although the use of particulate
drawings is being promoted by science education researchers,
instructors who choose to use them in their instruction need to be
made aware of the results of this research and what it can tell
them about student learning in the classroom. Educational psy-
chology research performed by Mayer and coworkers (Mayer &
Gallini 1990; Mayer & Anderson 1991, 1992) suggests that
instruction using computer anima- tions is most effective when the
words and pictures are presented simultaneously, rather than
separated from one another in time or space. Greenbowe et al.
(1995) reported that in order for students to have enough time to
interpret the particulate drawings included in computer animations,
these animations should be shown successively at least three times
(with narration) to the students. They also reported that students'
abilities to interpret particulate draw- ings in computer
animations greatly improve as their exposure to these drawings and
animations increases.
Unfortunately, instructors who choose to incorpo- rate computer
animations and particulate drawings in their instruction and
assessment may encounter difficulties. It can be very difficult for
instructors to create particulate drawings that faithfully
represent the scientific phenomena and that test the concepts of
interest (Sanger & Greenbowe 2000). Another problem instructors
may face is that because students are unfamiliar with particulate
drawings, they may misin- terpret these drawings. For example,
students in this study misinterpreted the drawings in the computer
animation depicting the osmosis of water through a semi-permeable
membrane into a syrup solution (Fig- ure 2) as suggesting that
sugar particles do not dissolve in water. In this case, the
students tried to interpret the molecular pictures using
macroscopic observations or definitions (Sanger 2000). Ulti-
mately, each instructor has to decide whether the additional
information that can be presented using particulate drawings and
computer animations
USE THE INTERNET TO TEACH BIOLOGY!
,B.oWe.b.,
Search
BioWeb Search: Internet .. ......... Biology Lessons
55 Activities in all Price: $29.95 areas of Biology
Also Available: Use the creativity of the web to help you
teachl
8io Tools High School Free teaching and Biology Activity Manual
curricular ideas. Visit
our web site at: Price: $29.95
www.healthscience.net
Health-Science Education, Inc. Meet the New (504) 897 - 0211
National Standards [email protected]
108 THE AMERICAN BIOLOGY TEACHER, VOLUME 63, NO. 2, FEBRUARY
2001
-
warrants the possible difficulties associated with using these
drawings and animations.
References Friedler, Y., Amir, R. & Tamir, P. (1987). High
school
students' difficulties in understanding osmosis. Interna- tional
Journal of Science Education, 9, 541-551.
Gabel, D.L., Samuel, K.V. & Hunn, D. (1987). Understanding
the particulate nature of matter. Journal of Chemical Educa- tion,
64, 695-697.
Gorodetsky, M. & Gussarsky, E. (1986). Misconceptualiza-
tion of the chemical equilibrium concept as revealed by different
evaluation methods. European Journal of Science Education, 8,
427-441.
Greenbowe, T.J., Sanger, M.J., Burke, K.A. & Lynch, M.D.
(1995). Results of Using Computer Animations on Conceptual Topics
in the Lecture Presentation and Their Effect on Student Performance
on Examination Questions. Paper presented at the national meeting
of the American Chemical Society, Chicago, IL.
Johnstone, A.H. & Mahmoud, N.A. (1980). Isolating topics of
high perceived difficulty in school biology. Journal of Biological
Education, 14, 325-328.
Krogh, D. (2000). Biology: A Guide to the Natural World. Upper
Saddle River, NJ: Prentice-Hall.
Marek, E. (1986). Understandings and misunderstandings of
biology concepts. The American Biology Teacher, 48, 37-40.
Mayer, R.E. & Anderson, R.B. (1991). Animations need
narrations: An experimental test of a dual-coding hypoth- esis.
Journal of Educational Psychology, 83, 484-490.
Mayer, R.E. & Anderson, R.B. (1992). The instructive anima-
tion: Helping students build connections between words and pictures
in multimedia learning. Journal of Educational Psychology, 84,
444-452.
Mayer, R.E. & Gallini, J.K. (1990). When is an illustration
worth ten thousand words? Journal of Educational Psychol- ogy, 82,
715-726.
Miller, K.R. & Levine, J. (1998). Biology: The Living
Science. Upper Saddle River, NJ: Prentice-Hall.
Nakhleh, M.B. (1993). Are our students conceptual thinkers or
algorithmic problem solvers? Journal of Chemical Educa- tion, 70,
52-55.
Nurrenbem, S.C. & Pickering, M. (1987). Concept learning
versus problem solving: Is there a difference? Journal of Chemical
Education, 64, 508-510.
Odom, A.L. (1995). Secondary & college biology students'
misconceptions about diffusion & osmosis. The American Biology
Teacher, 57, 409-415.
Odom, A.L. & Barrow, L.H. (1995). Development and
application of a two-tier diagnostic test measuring college biology
students' understanding of diffusion and osmosis after a course of
instruction. Journal of Research in Science Teaching, 32,
45-61.
Pickering, M. (1990). Further studies on concept learning versus
problem solving. Journal of Chemical Education, 67, 254-255.
Raven, P.H. & Johnson, G.B. (1999). Biology (5th ed.).
Boston: McGraw-Hill.
Russell, J.W., Kozma, R.B., Jones, T., Wykoff, J., Marx, N.
& Davis, J. (1997). Use of simultaneous-synchronized
macroscopic, microscopic, and symbolic representations to
enhance the teaching and learning of chemical con- cepts. Journal
of Chemical Education, 74, 330-334.
Sanger, M.J. & Greenbowe, T.J. (1997). Students' misconcep-
tions in electrochemistry: Current flow in electrolyte solutions
and the salt bridge. Journal of Chemical Education, 74,
819-823.
Sanger, M.J. & Greenbowe, T.J. (2000). Addressing student
misconceptions concerning electron flow in aqueous solu- tions with
instruction including computer animations and conceptual change
strategies. International Journal of Science Education, 22,
521-537.
Sanger, M.J. (2000). Using particulate drawings to determine and
improve students' conceptions of pure substances and mixtures.
Journal of Chemical Education, 77, 762-766.
Sawrey, B.A. (1990). Concept learning versus problem solv- ing:
Revisited. Journal of Chemical Education, 67, 253-254.
Strauss, E. & Lisowski, M. (1998). Biology: The Web of Life.
Menlo Park, CA: Scott Foresman Addison Wesley.
Westbrook, S.L. & Marek, E.A. (1991). A cross-age study of
student understanding of the concept of diffusion. Journal of
Research in Science Teaching, 28, 649-660.
Williamson, V.M. & Abraham, M.R. (1995). The effects of
computer animation on the particulate mental models of college
chemistry students. Journal of Research in Science Teaching, 32,
521-534.
Zuckerman, J.T. (1994). Problem solvers' conceptions about
osmosis. The American Biology Teacher, 56, 22-25.
Zuckerman, J.T. (1995). Use of inappropriate and inaccurate
conceptual knowledge to solve an osmosis problem. School Science
and Mathematics, 95, 124-129.
4ssroow Ovk
Hands On Science! Holbrook Field Study Courses
Investigate: * Biodiversity Issues * Ethnobotany
* Natural Resource Management * Geology ^ Terrestrial and
Aquatic Ecosystem Studies
* Courses throughout Latin America and Africa * Free leader for
every seven participants
* Professional Development Seminars
Call us today! 888-890-0632 HOLBROOK 3
Enriching Lives Through Travel Since 1 974
www.holbrookeducationtrips.com/abt.htm
_ S
DIFFUSION & OSMOSIS ANIMATION 109
Article Contentsp. 104p. 105p. 106p. 107p. 108p. 109
Issue Table of ContentsThe American Biology Teacher, Vol. 63,
No. 2 (Feb., 2001), pp. 81-144Front Matter [pp. 81-103]Guest
EditorialWe Teach Biology Backwards [p. 82]
LettersThe Myth of the "Biogenetic Law" [p. 84]Genus of Cover
Frog Clarified [p. 86]Medical History in Question [p. 86]
Technology Instead of a Textbook: Alternatives for the
Introductory Biology Classroom [pp. 89-94]Technology in the
Freshman Biology Classroom: Breaking the Dual Learning Curve [pp.
96-101]Can Computer Animations Affect College Biology Students'
Conceptions about Diffusion & Osmosis? [pp.
104-109]How-To-Do-ItBreaking out of the Box: Teaching Biology with
Web-Based Active Learning Modules [pp. 110-115]Making Pages That
Move: Applications of Dynamic HTML in the Biology Laboratory [pp.
116-118]Use of a Digital Camera to Document Student Observations in
a Microbiology Laboratory Class [pp. 119-123]Wind Stress: An
Experimental Investigation into the Structure-Function Relationship
of Leaf Architecture [pp. 124-127]Pipetting: A Practical Guide [pp.
128-131]
Biology TodayPure Joy [pp. 132-135]
Classroom Technology ReviewsReview: untitled [pp.
136-137]Review: untitled [pp. 137-138]
Book ReviewsHistory of MedicineReview: untitled [p. 139]
Deep-Sea EcologyReview: untitled [pp. 139-140]
Animal BehaviorReview: untitled [p. 140]
Scientific FraudReview: untitled [p. 140]
ConservationReview: untitled [p. 141]
Back Matter [pp. 142-144]