Core Unit: Fossils and Rocks
This unit combines the Earth Science and Life Science broad fields. Students will acquire an understanding of processes of rock formation. The study of fossils gives students another perspective of geologic time, allowing them to examine evidence of plants and animals which existed on the Earth a long time ago. In the unit, students should be able to gain an understanding of how scientists make inferences from indirect observations.
In grade 1 students learn about the planet Earth. The Optional Unit on Classifying Matter may also be of use in studying fossils and rocks.
The Optional Unit in grade 2 dealing with Dinosaurs is directly related to the study of fossils.
In grade 4, the Optional Unit on Vertebrates and Invertebrates is related to the study of fossils.
In grade 5 students investigate Resources. By understanding how rocks are formed, students may begin to appreciate the origins of fossil fuels. The Optional Unit on Machines and Work in grade 5 can also be related to some of the forces occuring in the Earth which cause rock formations to form and to move.
The grade 6 unit on Earthquakes and Volcanoes is very closely related. The dynamic changes taking place within the Earth's crust over long periods of time are responsible for rock formation. The Optional Unit on energy uses is indirectly related, since it can be referenced back to the grade 5 Core Unit dealing with Resources.
change, dinosaurs, fossils, rocks, soil, then and now
Work some modelling clay until it is soft. Shape it around a bone or a sea shell. Gently peel the clay back. The impression formed in the clay represents a mold fossil. Prepare a plaster of Paris mixture by adding plaster of Paris to water until the mixture has the consistency of buttermilk. Pour it into the modelling clay impression and allow it to harden. The artifact formed by the plaster of Paris represents a cast fossil. This can be taken one step further, if desired. Put a thin layer of petroleum jelly on the plaster of Paris impression. Surround the artifact with a cylindrical sheet of construction paper. Pour plaster of Paris mixture into this cylinder. When it hardens, gently separate the two impressions. The first one made represents the cast fossil (it has the same shape as the original organism) and the second one represents the mold fossil.
Make a cylindrical mold about 10 cm tall and about 4 cm greater in diameter than the maximum width of a shell. Press it into a sand base. (This just keeps things from leaking out the bottom.) Half-fill it with plaster of Paris. Allow the plaster of Paris to set for about three minutes. Then press a clam shell or oyster shell horizontally on the plaster. The lower side of the shell which first makes contact with the plaster should be covered with petroleum jelly. Pour more plaster of Paris into the cylinder, covering the shell. Colour this second layer of plaster of Paris with food colouring, to make the two layers more distinguishable.
Once the plaster has dried thoroughly overnight, remove the cardboard cylinder. Chip away at the plaster using a hammer and a chisel, working through the plaster in the approximate location where the shell is located. (Wear safety glasses for this.) If there is only a small amount of plaster surrounding the shell, the two halves may break away cleanly. The objective is to have the shell embedded in one piece of the plaster, and the mold remaining in the other half. This is analogous to some of the fossil impressions that are left in sedimentary rock.
The activity can be related to Arts Education. When a bronze cast of an object is made, a replica made of wax is prepared first, and a plaster mold is then made around the wax. The wax is melted from within the plaster and removed through narrow channels. Molten bronze is poured into the mold. After it cools, the plaster is removed.
Another way to relate the activity to Arts Education is by explaining that often people who have learned special technical skills can apply them in science for a variety of reasons. The quality of the artifacts produced in this activity, for instance, depends on the techniques used by the students.
Fossil formation can be more readily understood if students undertake this type of simulation activity. If samples of fossils formed in shale are available, they can be compared to the mold and cast reproductions formed in the plaster of Paris and modelling clay.
In the activity, the shell (simulating the organism fossilized) was covered by plaster (simulating rock) very quickly. Ask students to consider whether the rock that covered the organism formed over the same period of time as in the activity performed. Try other ways to enable them to relate the activity performed to the actual processes which took place in order to cause the fossil to form.
Factors: A2, B1, B4, B10, B15, C3, C9, C12, F5, G1
Objectives: 2.1, 2.3, 2.4, 3.1
Assessment Techniques: 1, 2, 3, 4, 5, 8, 9
Involve students in the planning and preparation for this activity.
Factors: A2, B1, C3, C12, F3, G1, G3
Assessment Techniques: 1, 3, 5
Common Essential Learnings: Independent
Learning. Students can discover for themselves the context of knowledge
by actively participating in a field trip. First hand evidence extends resource-based
learning to actual field experience. This gives students an accurate sampling
of activities that historians and palaeontologists undertake when doing
on-site information gathering. (Perhaps an expert in the field could be
invited to come to speak the students in the class.) It helps to give them
an appreciation of science, and promote life-long learning and interest.
Guide students through the various processes needed to complete this assignment.
Work with your teacher-librarian, if available, to plan, teach, and evaluate
components of this assignment.
Objectives: 2.1, 2.2
Assessment Techniques: 1, 2, 3, 4,
5, 9
Common Essential Learnings: Independent
Learning, Communication,
Assemble a variety of molds, such as tart cups, plastic margarine containers,
egg cartons, milk cartons. Pour plaster of Paris into the molds. Wait a
few minutes for them to set partially. Place one or more bones in each mold
and pour in some more plaster. (You might want to make one or two samples
that do not have bones in them.) Allow each to set for several hours. As
an alternative, prepare a few "bone fields" by placing a large number of
bones into a bigger tray.
Once all of the plaster molds have been prepared, divide them among the
student groups. Students pretend they are palaeontologists at a site. Tell
them that it is suspected that there might be fossils in the samples they
have. One problem is that there is no way of knowing for sure if there is
a fossil in the sample. Another problem is removing the plaster (simulating
rock) very carefully, so that if there is a fossil inside, it can be removed
without damage.
Make sure that students wear safety glasses while they chip away at the
plaster to discover the "fossil." They can use screwdrivers as chisels,
tapping them with small mallets or hammers. Sandpaper can be used to remove
the material very close to the specimen. The petroleum jelly placed on the
bones when the casts were made makes the removal of the plaster easier.
If the bones from an entire animal were used to prepare the "fossils",
students can try to piece them together to identify the type of animal they
might have come from. Silicon caulking or wire can be used to hold the bones
together. If a few of the bones are missing (as often happens in actuality),
students can predict the shape and size of the missing bones. Modelling
clay can be used to make the missing bones, so that the entire skeleton
can be pieced together.
(Note: Instead of using plaster of Paris, wax may be used instead. It
is an easier material for students to work with. Heat paraffin wax in a
double boiler. For coloured layers of wax, melt a few crayons in the wax.
Keep the hot wax away from open flames. Prepare molds prior to the activity,
to eliminate any risk of students being near molten wax. Reuse plastic dairy
food containers as molds. Partially fill the molds with molten wax. Allow
the wax to cool slightly. Once a solid layer has formed on top, gently place
the bones on top. Reheat the remaining wax and pour it over the bones to
complete the molds. Once the wax hardens, remove the molds. Students can
use popsicle (tm) sticks or nails to chisel away at the wax. Ensure that
all students take part in the search for bones and in reporting data to
the class.)
It is possible to introduce and incorporate bison "kill sites" into this
activity. Interesting finds have been discovered at these sites. Two examples
of sites are Besant (between Regina and Swift Current) and the Wanuskewin
Heritage Park near Saskatoon. These places would be worth visiting.
Factors: A2, B1, B4, B15, C1, C3, C8, C9, C12, F2, F3, F5,
G1, G2, G3
Assessment Techniques: 1, 3, 4, 5, 7c, 8
Common Essential Learnings: Critical
and CreativeThinking. This activity is similar to some of the quarry
work actually done by palaeontologists. It provides students with an authentic
view of what some scientists and technicians do in order to further knowledge.
Students get a realistic presentation of how knowledge is advanced in science.
They may also perceive the inaccuracies in the stereotyped portrayal of
scientists as men, having grey hair, being slightly demented, wearing white
lab coats, working frantically in laboratories on bizarre experiments.
The activity also reveals that once fossil evidence has been uncovered,
the knowledge obtained from that evidence is still tentative and subject
to close scrutiny. Different theories can and do develop based on the same
fossil record.
In this activity, students relate their learning in class to a real life
experience and see science being pursued within a social context. By seeing
an individual engrossed in the pursuit of a science-related activity, students
may recognize the potential that science has for nurturing a life- long
interest in the pursuit of knowledge.
Factors: A2, B4, C3, C12, F2, F3, G1
Assessment Techniques: 1, 3
Factors: A2, B4, B15, C1, C3, F2, F3, G1, G2, G3
Objectives: 1.2, 2.1, 2.2, 2.4, 3.1
Assessment Techniques: 1, 3
Common Essential Learnings: Independent
Learning. Museums are wonderful places, designed to be enjoyed and appreciated
by all. They provide the school with a valuable resource, making it possible
for students to have experiences not easily duplicated within a school.
A visit to the local museum can enrich learning and provide an opportunity
to explore ways that are available for them to extend their learning on
their own, out of school.
An overnight campsite can be obtained at Dinosaur Provincial Park, which
is about an hour's drive from the museum. The park has interpretive trails
and naturalists who lead tours. The park has some splendid geological formations.
Tours can be arranged to visit sites in the park where dinosaur bones are
being excavated by scientists, technicians, and university students.
An excursion such as this, in spite of the distance, is an experience
that students will remember long after they complete their formal schooling.
Enriching experiences such as these are the most pleasant and memorable
ones, retained for a lifetime. Fund raising for a major trip is also a valuable
learning experience.
The class can be involvoed in the planning required for such an important
project
.
The Museum of Natural History, the Saskatchewan Science Centre in Regina,
and the Museums of Geology and Biology at the University of Saskatchewan
are other interesting places to visit. They provide students with a fascinating
science excursion, though perhaps less related to this Core Unit as a trip
to Drumheller would be.
Factors: A2, B1, B4, B15, C1, C3, C8, C9, C12, F2, F3, G1,
G2, G3
Objectives: 1.2, 2.1, 2.2, 2.4, 3.1,
3.2
Assessment Techniques: 1, 2, 3, 4, 5, 6, 7,
8, 9
Have students examine each group of samples. Indicate that the rocks in
each group have been classified in a certain way. It is up to them to try
to find out how they have been classified. Students should be looking for
any distinguishing features of the rocks found in each group which make
them distinct from the rocks found in the other two groups. They may come
up with a variety of interesting responses when given this problem to solve!
Consider their responses. None of the groups may be close to determining
how the rocks have been grouped. If not, perhaps you could tell them that
the rocks are grouped according to how they were formed. Then provide them
with another opportunity to develop a hypothesis of how the rocks in each
group were formed. Have the class consider each hypothesis, commenting on
its strengths and weaknesses.
Students will indepemdently develop several different classification schemes.
Each may have inherent advantages which should be explored.
Factors: C1, C3, C8, C9, C12, F3, F5, G1
Assessment Techniques: 1, 2, 3, 4, 5, 7c, 8 Common Essential Learnings: Critical
and CreativeThinking. If students were given the task of classifying
the rocks themselves, according to how they were formed, they would have
to be cognizant of the main distinguishing features of igneous, metamorphic,
and sedimentary rocks. The whole point of the activity would then vanish!
There would be no hypothesizing, and few opportunities for conjecture. Critical
thinking would not be promoted. By presenting the rock samples after they
have already been classified, students are attempting to determine the rules
or criteria that were used in the classification. In this case, this is
far more interesting and appealing, since it presents students with a challenge
that will engage and stimulate their curiosity.
This suggests that quite often the way in which a particular lesson is
planned and structured is crucial in determining the outcome as well as
the ways in which the Common Essential Learnings will be developed.
There are variations of this activity. The mineral can be scratched on
a porcelain streak plate to examine the colour of the dust produced. Sometimes
the dust will be a different colour than the mineral. The rocks and minerals
from the previous activity could be used in the same groups in which they
were classified, to build upon ideas relating to classification.
In a scratch test, two minerals can be rubbed against one another to see
if one will scratch the other. The one which ends up being scratched is
not as hard as the other. This test enables the minerals to be arranged
in order of hardness.
(Minerals are arranged in order of hardness on a scale of 1 to 10. For
comparison, a fingernail has a hardness of about 2.5, so if a rock will
scratch a fingernail it has to have a hardness which is greater than 2.5.
Similarly, a copper penny has a hardness of about 3, while a steel knife
blade has a hardness of about 5.5. For reference, the Mohs' Scale of mineral
hardness, which can be found in any geology textbook, is shown below.)
For an extension of this activity, in addition to streak and scratch tests,
students could do other tests on the minerals, such as an acid test, by
placing the mineral in vinegar to see if it changes. There is computer software
available which asks a series of questions about a mineral, including such
things as hardness, which, when answered, help identify the mineral. Investigate
the possibility of using Computer Assisted Learning software where appropriate.
Correctly identifying some of the less common minerals can be a challenging
task. However, making a correct identification is only of peripheral importance
in this activity. Of more importance is that students recognize that problem
solving can by systematized into small, incremental procedures, each of
which is relatively simple, but when taken together are able to solve a
much more complex problem, which would be more difficult to solve otherwise.
Factors: A2, B10, C1, C3, C9, C12, E5, F2, F3, F5, G2
Assessment Techniques: 1, 3, 4, 5,
7, 8, 9
Factors: B1, B10, C3, C8, C9, C12, F3, F5, G2
Assessment Techniques: 3, 5, 8
Common Essential Learnings: Numeracy.
Measurement and calculations is emphasized in this activity. Once the difference
in mass is determined for all the samples, students need to develop a method
of comparing the changes of mass in each smaple, since the masses of the
rock samples were likely not the same to start with. Ratios can be used
to express the proportion of water in the sample after it had been soaked.
The amount of water can also be expressed as a percentage of the total mass.
Students can examine the crystals with hand magnifiers. They should sketch
the shape of the crystals. If the variation with cooling taking place quickly
and slowly was done, they should develop a hypothesis to account for any
differences observed in the crystal formation.
Crystals reveal different patterns of symmetry. Some of the more common
shapes are cubic, hexagonal, tetragonal, monoclinic, orthorhombic, and triclinic.
Locate a diagram and prepare a large poster for the classroom, which will
provide students with the information they need to recognize these shapes.
Examine some rocks to see if crystal patterns are evident within them.
There are many good books available on rocks and minerals, with photographs
of crystal structures. Refer to the Bibliography for elementary science.
To relate crystallography to the study of rocks, point out that there
are some naturally occurring minerals which have regular, crystalline shapes.
The activity serves as a model of how crystals form in nature. However,
it might be pointed out that it takes long periods of time for the crystals
to form naturally.
Factors: B1, B10, B15, C3, C8, C9, F5, G1
Assessment Techniques: 1, 3, 5, 8
Common Essential Learnings: Critical
and Creative Thinking. Students might wonder why some crystals have
different shapes. For an enrichment activity, pose this as a question. Allow
students to suggest possible explanations.
There may be students who are not able to understand what this activity
has to do with rocks. The connection should be made by showing students
rocks which have a crystal structure and asking them to speculate about
how the rocks came to be crystalline.
Factors: B1, B10, B15, C3, C12, F3, F5, G1
Objectives: 1.2, 1.3, 2.1, 3.2
Assessment Techniques: 1, 3, 5, 7c,
8
Common Essential Learnings: Critical
and Creative Thinking. Students will conclude how sedimentary rock forms.
Several distinct layers form, with the larger, heavier material being at
the bottom.
The location of the shells can be considered to be analogous to fossils
being found in distinct layers in sedimentary rock, though not necessarily
for the same reason as this model might suggest. This last point is very
important. While models serve a variety of uses in science, they do have
their limitations. If the model is subjected to close scrutiny, its accuracy
in portraying reality may begin to break down. Models are only rough approximations
at best. For instance, the build up of sedimentary layers in this model
occurs within a few minutes; the build-up of sediment to form rock occurs
over a time span of hundreds of thousands of years. The many different events
of this longer time frame limit the accuracy of this model.
Pour off any remaining water and remove the hardened material. To do this,
securely wrap the jar in a cloth and strike it with a hammer to break the
glass. (Use gloves and safety glasses to do this. Students should not perform
this step, and should not be nearby when the jars are being broken.) Carefully
remove the cloth and any small pieces of glass. Have students examine the
material which has been formed. They should refer to the poster to determine
when and how each of the layers was formed.
This activity is a good model of how sedimentary rock is formed. Have
the students examine a sample of sedimentary rock and compare it to the
material which was made in class.
Factors: A2, B1, B15, C3, C12, F2, F5, G1, G2
Assessment Techniques: 1, 3, 5, 7c,
8 Common Essential Learnings: Critical
and Creative Thinking. This concrete activity will enable students to
think critically about an abstract concept such as sedimentary rock formation.
During this stage of a child's development, a wide variety of concrete experiences
should be explored.
Continue this activity back in the classroom. Have each student bring
a cardboard egg carton to school to store the rocks. The rocks can be examined
closely and identified, if possible. Students can classify their rocks in
different ways.
An extension of this activity is to twin the class with a class elsewhere
in the world. Correspond back and forth. Send a small parcel to students
in the other class, including stories about the trip, drawings of interesting
activities or occurences, and samples of the rocks that were collected.
Those students will have a collection of rocks found in Western Canada.
Perhaps your class will receive samples of rocks that are commonly found
elsewhere in the world. If so, have students compare them with the rocks
they found. As an added challenge, they can try to identify those rocks.
For this activity, twinning between classrooms in the northern and southern
parts of Saskatchewan would be interesting, since rocks vary so much throughout
the province. Students can share information about what they are doing in
other subjects as well.
If the twinning project is undertaken, students may develop an understanding
of people from different backgrounds and cultures.
Factors: C1, C3, C9, C12, F2, F3, G1, G2, G3
Assessment Techniques: 1, 2, 3, 4,
5, 6, 7, 8, 9
Consider twinning during this project, to obtain soil samples from students
who live in a different parts of the province.
Factors: A2, B1, B4, C3, C9, C12, F3, G1, G3
Assessment Techniques: 3, 4, 5, 8,
9
Common Essential Learnings: Critical
and Creative Thinking. Students can begin to wonder about what caused
rocks to break up to form soil. Ideas from grade 3 which deal with soil
and weathering can be reviewed.
Customary courtesies should be extended to an Indian elder. Offer transportation
if the elder accepts an invitation to visit the classroom. Arrange to provide
a gift in exchange for information or service. Emphasis should be placed
on sharing. During oral communication, students should ask a question and
allow pause time for the question to be reflected upon before an answer
is given. Permission to photograph or videotape the demonstration should
be obtained beforehand. Other courtesies that are normally offered to any
visitor to the school should be extended.
Objectives: 1.1
Assessment Techniques: 1, 3, 5
Common Essential Learnings: Personal
and Social Values and Skills, Technological
Literacy. This activity supports students in interpreting the social
and cultural aspects of science. Because of its characteristic properties,
flint has been an important material in the development of technology. Early
hunters used flint to make knives, spears, axes, and arrows. It was also
used to make fires.
Have students go on a fossil hunt along the outside wall of a building!
Bring along some modelling clay. If you check with the building security
people, they may permit you to take impressions of the fossils. Push the
clay into the stone to form an impression of the fossil. Remove the clay
from the wall. Use an old toothbrush to remove any reside from the building.
Make plaster impressions of the modelling clay patterns, to obtain an
exact replica of the fossil pattern, as it appears in the limestone facing.
(This would also be an interesting way to record permanently some information
on the cornerstone of a building.) Examine limestone facings on buildings
in your community for evidence of fossilization.
Instead of using modelling clay, have students draw sketches of the impressions
on the wall, or use a camera to take photographs.
Factors: A2, B1, B4, C3, C12, F3, G1, G3
Assessment Techniques: 1, 3, 4, 5
Common Essential Learnings: Critical
and Creative Thinking. The activity enables students to examine ways
in which knowledge is extended in science. Unanticipated, but important,
discoveries occasionally result through circumstances such as quarrying
for gravel, or excavating for a building foundation or road. All it takes
is someone with the presence of mind to sense that the remarkable does exist
within the ordinary. Some of the most amazing discoveries in science have
been stumbled upon in this way. Serendipity has its amusing way of adding
to the body of scientific knowledge.
If you need a set of slides illustrating rock formations, have the secondary
teacher assign to a group of students the project of photographing locations
with interesting geological features. Similar projects at other grades include
topics such as magnets in use, simple machines, corrosion, gardening, farming,
and animal habitats.
Factors: C3, C12, F3, G1, G2, G3
Assessment Techniques: 2, 3, 5
Common Essential Learnings: Personal
and Social Values and Skills. In a project like this students work cooperatively
with others. In a small rural school, a project like this helps make the
older and younger students feel more comfortable with each other. A caring
climate can develop, leading to a greater appreciation of the school by
students, parents, and other members of the community.
. The museum, located near the Red Deer River in Alberta's
badlands, is one of the finest museums of its kind in the world. It is a fascinating
place. Inside, a wide range of information pertaining to natural history is
presented. The museum is located in a region where many fossil discoveries
have been made.
. (Kits containing samples are available
from several sources.) Prior to the activity, classify the samples as igneous,
sedimentary, or metamorphic. Arrange the rocks accordingly.
Mohs' Scale of Mineral Hardness
1
Talc
Soft, flakes on fingers
2
Gypsum
Scratched by a fingernail
3
Calcite
Scratched by a penny
4
Fluorite
Scratched by a knife blade
5
Apatite
Barely scratched by a knife blade
6
Feldspar
Can scratch glass
7
Quartz
Can scratch a steel file
8
Topaz
Can scratch quartz
9
Corundum
Can scratch topaz
10
Diamond
Nothing else can scratch it.
.
As a variation of this activity, two identical samples of the hot solutions
could be prepared. Cool one rapidly, by placing the cup in an ice-water bath,
and allow the other to cool more slowly. Compare the crystals that have formed
in each cup.