Digital Imaging in K-12 Biology
James Ekstrom, Phillips Exeter Academy

http://science.exeter.edu/jekstrom/default.html
K-12 instruction in biology has traditionally taken a very descrip-

tive approach. This is in marked contrast to quantitative as well as
qualitative way of looking at things in physics and chemistry. This
qualitative/descriptive approach even extends into the iaboratory
portion of the biological course. One way to introduce a more
quantitative approach is in the microscopy portion of the biology
curriculum. Because cellular structure is primarily a microscopic
province It makes ...... .,t„..,......_,....,..,„,.,...........:. _•.-.•..-.-,-. -,..,,•.,_.-.-._•
sense to introduce j
students to the
different micro-
scopic tools such
as TEM and SEM,
as well as the light
microscope that are
used to investigate
cell structure. It is
easy to quantify
microscopic work
and the light micro-
scope is the prin-
ciple, if sometimes
only instrument,
found in biology
classrooms.

A typical in-
troduction to the
microscope can
involve a mea-
surement of the
"field of view," as
well as getting
use to the various
controls found on
the instrument. If
the lowest power
student objective is
4X and the ocular
10X this measure-
ment can occur with
a fair degree of ac-
curacy using a 6"
mass-produced
plastic ruler that
also has a metric
edge to it. Using a
higher power objec-
tive would involve
mathematically
calculating what
the field would be
or using an inex-
pensive $15,00)
micrometer. Once
the student makes

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100X and 400X they can record them and keep them with the
microscope. At some future point if a "wee beastie" should occupy
one-half of their field under 100X then they would have an approxi-
mate size of the object.

The advent of inexpensive digital photography allows the In-
structor to carry out a more sophisticated approach to this exercise.
Digital images of the three fields of magnification can be stored as
calibrations for that microscope. A subsequent microscopic image
can be digitized and the reference scale for that magnification can
be cut and pasted on the image.

[Figure 1] Cheek cells stained with methylene blue that has
been photographed with the relevant scale pasted on the image.
This calibrated image can be printed and passed out to students
as an introduction to measurement. The students would simply
be given the sheets, told to work in small groups and allowed to
have string and a millimeter ruler. Their goal is to determine the
length of the cell. A discussion follows bearing on the accuracy of
their results. A very recent plug-in from ReindeerGraphics makes
it possible to directly calibrate the image you are working on. http:
//reindeergraphics.com/ The same calibrated image can then be
brought up under one of the following freeware programs; Scion
Image (PC), http://www.scioncorp.com/ NIH Image Mac, or imageJ.
http://rsb.info.nih.gov/ij/

The application that is realiy coming into its own is ImageJ,
This JAVA based applet can be used as a free-standing application
or Incorporated into a WEB page. Students carrying out the above
exercise in any of these applications can compare their results to
what they received on the paper exercise. After calibrating their im-
age, they can measure the area and perimeter of various structures
and then compare these measurements to other ways of looking at
the cheek cell like the SEM image shown in Figure 2[1]. A teacher
using ImageJ can put class results on the internet and allow the
students to interpret their results and write-up their conclusions

[Figure 4]. (Top) Elm Sawfly
[Figure 5} (Bottom) LM and SEM view of Barn Spider.

32 O I I C R O S C O P Y T O D f l Y November/December 2002

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after the laboratory
period.

The biggest
hurdle to the use of
quantitative work in
secondary school
biology, with specific
reference to digital
imaging, is training
teachers in the use of
this technology and
seeing that the ex-
ercises "fit-in" to the
curricular standards.
[2][3] This training
"problem" becomes
particularly marked in
working with elemen-
tary school students
and teachers. With
the students it is just
a question of catch-
ing their attention.
However, with teachers it is trying to provide different levels of tech-
nology that they are are reasonably comfortable with. i.e. more paper
and pencil exercises that lead to quantitative evaluations that can be
made on the WEB.

The "Ugly Bug" contest that I ran this year was an attempt to
introduce these same quantitative measuring skills into a K-8 science
curriculum. Bugs are probably second only to dinosaurs in interest to
most elementary students, in this contest I wanted to expand on some
of the efforts that I had seen in a couple of state "Ugly Bug" contests
[4][5] and include measuring exercises that the students could do with
the bugs they collected. Subsequently they could compare their results
with other school examples on the WEB,

The Educational Consultant for the State of New Hampshire agreed
to mail out announcements of the contest to all elementary school
principals. The announcement mailing included a description of contest
prizes as weil as a return postcard that a teacher in the school sent back
announcing his or her classes' interest In participating. I e-mailed the
teachers the rules and regulations for the contest and sent every class
an "Ugly Bug Contest" poster to inspire them in their quest.

After members of a class collected several bugs they had to as a
group choose the one they wanted to enter in the contest. Then they
had to classify it as best they could. This invariably involved the school
librarian orteacher assisting them in WEB searches to identify the bug.
My "Ugly Bug" web site also furnished them with links to various groups
and university databases. Some schools invited in parents and friends
who had bug collections. The dead entry was then sent to me along
with the classes best shot at classification.

On receipt of the bug I photographed it with a varying assortment
of reflecting light microscopes plus a digital camera shot that incorpo-
rated a metric ruler for calibration purposes [Figure 4 (top)]. Typical
digital photograph "Elm Sawfly" Then the mounted bug was dried,
sputter coated and examined in the scanning electron microscope. I
identified the submitted bugs and determined the winners. Emphasis
was placed on the apparent effort that the students had made in clas-
sifying their entry.

At the end of the contest each participating school received an
11" x 17" laminated poster of LM and SEM views of their bug [Figure

5]. They also received their "golden" bug back along with a couple of
paper measuring exercises involving either a light microscope or SEM
view of their entry. See a fine example of a student poster, left, from
Stratham School, Stratham, NH.

The class was directed to the Results WEB site[6] where they
could see a LM view of their school's entry, plus all the other entries.
On this same page was an ImageJ applet that came up and allowed
students to view a variety of SEM bug images and answer the mea-
surement questions.

The science supplier VWR had previous agreed to donate a good
Stereo Microscope and two OK stereo microscopes as prizes. This took
care of the first three prizes. All participating schools received laminated
charts of various insects. The New Hampshire Science Teachers had
a conference at Phillips Exeter at the end of March, 2002.1 presented
an imaging workshop at the conference and discussed the results of
the contest with conference participants. On the basis of that feedback
a decision was made to have an "Ugly Bug" contest next year. P.S. It
was made clear at the end of the contest that there is no such thing
as an ugly bug. •

References:
[1] j , Eksirom http://science.exeter.edu/jekslrom/WEB/CELLS/Epith/

Epitri.html
[2] J.Ekstrom Cell Structure Study, The Science Teacher Vol 67, No. 7, Oc-

tober 2000 htlp://sci en ce.exeter.edu/jekstrorn/nsta/el odea, htm I
[3] J. Ekstrom Slicing for Biology, The Science Teacher Vol 68, No. 2, Feb.

2001
[4] Marilee Sellers NAU "Ugly Bug" Contest http://wvvw.nau.edu/%7Eelectron/

bug/99/99.html
[5] Oklahoma Microscopy Society "Ugly Bug" contest http://

www.uglybug.org/
[6] New Hampshire "Ugly Bug" contest http://science.exeter.edu/jekstrom/

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