FOSSILS IN THE CLASSROOM
Jon O. Garbisch
Department of Geology
University of Kansas
Lawrence, KS 66045
Level: Elementary to junior high
Anticipated Learning Outcomes
- The student will acquire a general knowledge of fossils
and paleontology, the study of evidence of life in the past.
- The student will be able to identify the major invertebrate
groups (phyla) commonly found in the fossil record.
- The student will learn how fossils tell us about the
history of the earth.
This activity is designed to provide a general knowledge
about evidence of life in the past and paleontology, or more simply, fossils,
with an emphasis on the invertebrate phyla which include over 95% of all
animal species. A general knowledge of life is all the students need; even
many five year olds know what a clam, snail, insect, starfish, or octopus
is and where these kinds of animals may live. The activity will introduce
the student to the science of paleontology and its intimate relationship
to sedimentary geology. The main concept here is that the organism interacted
with the rock-forming environment. Information is preserved in the sedimentary
rocks and the fossil remains. The information in one is very important in
our understanding of the other. The activity also introduces the student
to what the professional paleontologist does to earn a living.
Your state geological survey, local geology society or
natural history museum often publish good introductory guides to the local
rocks or sell general introductory books for the hobbyist. Ideally, I recommend
the instructor take at least one introductory course in geology or read
a few introductory books on the the subject. Many universities offer introductory
geology courses in the summer. I do believe a general knowledge of biology
and a long evening of reading would suffice for the simpler parts of the
exercise, especially if you can find a local geologist willing to help.
- Rocks - Obtain good examples of sandstone, shale and
limestone, the three main kinds of rocks fossils occur in. Ideally the
rocks will contain a few fossils.
- Tools - A hand lens or magnifying glass for each student
can be very useful, the cheap ones ($2-$5) are very durable and just as
good as the more expensive kinds for most purposes. I think the student
feels more like an explorer or scientist with a hand lens to magnify the
very small but often abundant fossils. Hammers are overrated and usually
do more damage than good in most activities.
- Fossil material - This can be a real problem. Fossil
collections from Wards Scientific or similar businesses are often expensive
and inadequate for use by more than two or three students at a time. They
are also easily damaged and lost. I advise using disposable material if
at all possible. The state geological survey, the geology department at
a local university or the local natural history museum often has a person
who is formally or informally assigned to public education. This person
can often help you find free fossil material or will help teach the session
and bring their own material. Some museums have rock and/or fossil kits
that they will loan out to the local schools which often include teaching
aids as well as specimens. The objective is a complete selection of most
of the major invertebrate groups, that is 8 to 12 different groups (phyla).
If you have trouble finding a specific group, a modern representative is
acceptable; the student still learns to identify the organism. In general
I feel the student should learn to identify and distinguish from other
groups: protozoans (microfossils), sponges, coelenterates (corals
etc.), bryozoans, brachiopods, annelids (mostly just worm
tracks or borings), arthropods (trilobites, insects, crustaceans,
etc.), echinoderms (sea urchins, starfish, crinoids, etc.), mollusks
(snails, clams, cephalopods, etc.). The bold-face groups are the
most common and easily recognized.
Many areas are rich in fossiliferous shales and limestones. For example,
here in the midwest a gallon of the appropriate shale layer contains thousands
of different kinds of small fossils in the 1-cm and smaller range. Often
outcrops of weathered limestone and shale are covered with a fine layer
of fossil material which can be swept up with a sturdy broom (consult your
local geologist about localities). Collect about five gallons plus of material
for every 20 students. Wash this material through some sort of screen to
remove the mud but keep the larger parts (>1 mm) (see part 3 of procedures).
Ideally, you and the class go out and do the collecting.
- Reference material - Any introductory book to fossils
covers the above topics in more detail than you will need. I find the Golden
Guide® Fossils to be very inexpensive and complete. The Golden Guide®
Fossils is complete enough to be used as a text and handy identification
guide for a one or two week segment in a general science course. It also
covers all the topics listed under the activities below. It is even used
in the paleontology for non-majors course at the University of Wisconsin,
This is a classroom activity on invertebrate fossils, but
if you have the time and money to go on a field trip, it is always the richer
learning experience for the student. This is especially true of geology
and paleontology which are fundamentally field sciences. The best activities
are those that simulate a field trip and have the same sense of exploration
for the student.
- Before starting a unit on fossils, a general knowledge
of sedimentary rocks and how these rocks have formed can be very helpful.
(For example, what is a sandstone? It is rock made of sand grains like
one would find on a beach or in a river.) The student can associate the
environment the rock formed in with the kinds of environments the fossilized
animal originally lived in. For example, shale usually starts as a soft
muddy bottom sediment in quiet water where fine mud can settle out. Animal
fossils found in shale are those that swam in the water above the muddy
bottom or were specially adapted to live on or in soft soupy mud. Have
the students think about how and where each kind of rock forms, and what
kinds of animals live in those environments.
- First introduce the students to the major invertebrate
phyla as listed above. If the students have already had a good introductory
biology class, you may only need to review. Often modern specimens can
be substituted here. You might want the student to keep a lab notebook,
with a drawing of a representative organism from each group and a list
of features which distinguish that group from others. This notebook can
be used by the student to identify fossils in other exercises. For example,
the student could draw a snail, labeling the opening and spire portions,
also listing features such as: spirally coiled shell, interior is a single
open chamber (which distinguishes most snails or gastropods). Ideally the
students will have a variety of specimens they can pick up and examine
closely. Ask questions which make the student think about the group of
features that determine which phyla a fossil belongs in.
- If you have access to fossiliferous limestones and shales
in your area that can be collected as described under materials, the following
exercise is almost as good as a field trip. Spread a thin layer of this
material out in a tray and have the students (in groups of two or three)
use a hand lens to pick and identify the major groups of fossils they find.
As an incentive let them keep anything they can identify. This activity
works very well after the major fossil groups (such as clams, snails, brachiopods,
echinoderms, etc.) have been introduced. The students are doing exactly
what many paleontologists spend lots of time doing. It helps if each student
can have a magnifying glass for the exercise, a tray or surface to spread
out the material and a zip-lock plastic bag to put the fossils in to take
them home. Good bright light is very important.
- An alternative or additional exercise is to acquire several
(one per every three or four students) plates of fossil bearing rock, at
least a foot square. Paleozoic age limestones commonly occur as thin flag
stones covered with a variety of fossils. Ask your local geologist about
where to find such material.
- In exercises 3 and 4 students identified the various
fossils. They could also note the association of certain organisms with
certain types of rock. For example, corals live in a marine environment.
If you find fossil corals in the local rocks, this is evidence that the
area was under an ocean when the coral was alive, and maybe the area was
once a little like the Bahamas are today. Have the students read about
modern coral reefs and the ocean around the Bahamas or the Florida Keys.
Have them think about the kinds of organisms that live in the ocean today
and whether they are similar to the fossils they are learning about. Is
it reasonable to think that 100s of millions of years ago the midwest was
like the Bahamas? (Many geologists think that is a good analogue for certain
times in the past.)
- Once the students can identify the major groups have
them pick a favorite specimen and do a small research project. They could
find out where the same kind of animal lives today and what type of environment
it prefers. Many paleontologists are more interested in what the fossil
can tell about the ancient environment than in the fossil itself. Have
the student give a short talk to their classmates about the fossil. For
example, if they have a fossil coral they can say it probably lived in
warm, clear water somewhere near the equator. If the fossil was collected
here in Kansas (and they are) how could there have been coral reefs here
in Kansas? The midwest certainly looks nothing like the Bahamas do today;
we don't even have an ocean! This makes the students realize that environments
in a particular location change through time.
- Some fossils represent organisms that only lived for
a specific span of time in the past or have only just appeared here on
the earth. The concepts of geologic time and biostratigraphic ranges (a
fossil found in a rock can represent a specific chunk of geologic time)
can be difficult to teach. It requires a fair background in geology and
paleontology. If you have the time and the material, you can illustrate
the concept fairly well. For example a rock with trilobite fossils in it
must be between 245-530 million years old (Paleozoic Era). (The Precambrian/Paleozoic
boundary is conventionally assigned an age of 570 million years; however,
recent studies indicate it is probably 530-540 million years ago.) If you
have specimens of the appropriate fossils students can learn to make an
approximate guess about the age of the rock each fossil was found in. Dinosaur
bones occur in Mesozoic age rocks, 65-245 million years old. This is an
important concept since it is on this idea that geologists originally constructed
the history of the earth. The book Golden Guide® Fossils covers this
topic very well.
Results and Discussion
I have tested these activities with students between six
and nine years old and they have been very successful. The activities would
also work well with older students. For background, students need to have
only a general knowledge of nature.
While dinosaurs will always be popular, invertebrate fossils can generate
an equal amount of student interest for several reasons. The invertebrates
living in the time of the dinosaurs can often tell more about the environment
than the dinosaur fossils themselves. Invertebrate fossils are common. Often
the student can collect and keep for their very own invertebrate fossils
they have found near their home. Like a dinosaur, an invertebrate fossil
is something from the distant past; some are 100s of millions of years older
than the earliest dinosaurs. I have found even the youngest students can
imagine the ancient ocean that was once here in the midwest when they find
a fossil oyster.
The principle objective of this activity is to help students identify fossils
they may find on a camping trip or in the gravel of a parking lot. Not only
might they pick up a fossil and go "wow a trilobite", they will
also have a sense of the ocean that must have covered the area and how very
long ago the trilobite lived.
Rhodes, F. R. T., Zim, H. S., and Shaffer, P. R., 1962,
Fossils: a guide to prehistoric life: Golden Press, New York, 160 p. (At
$4 this is an inexpensive and comprehensive guide to fossils, with good