A Lesson Plan on Fossilization
Lesson: What is Fossilization?
Notes for the leader/teacher:
We recommend that you say as little as possible in each lesson, giving
your students opportunities to think and express their own ideas.
Dialogue is included in bold and italics. Things you would do during the lesson are in CAPITAL LETTERS.
Goal: To experience how fossils are formed
- An inexpensive fossil if you have one.
- Shrimp shell (A workable fossil substitute)
- Escargot shell (A workable fossil substitute)
- Plaster of Paris
- Pitcher of water
- Fine sand- must be fine enough to go through the sifter
- Waterproof container-small disposable aluminum baking pans work well.
- Small plastic or rubber dinosaur
lesson plan has 2 parts. For part 2 click on the link at the bottom of
the page that reads fossilization Lesson Plan Part 2; Fossil Excavation.
Part 1; The Process of Fossilization
the lesson: Mix a small amount of fine sand with the plaster of Paris.
DO NOT ADD WATER. Put about a third of the dry mixture in a water proof
container. Separate the remaining mixture into two containers. Mix a
small amount of dry tempera paint to create different shades of brown.
Mix the colors into the containers to make two distinct colors of
powdery sand so the layers will show as different “soil” as it is added.
Introduction To Fossilization:
- PASS AROUND
SOME SAMPLE FOSSILS. If possible, have examples of both cast and mold
varieties. For an even better impression, try to have a sample that is
the positive/negative impression of both cast and mold of the same
fossil. How are fossils formed? What do you notice about these
fossils? What seems the same? What seems different? How do you think the
discussion could include experiences they might have had: making
playdoh molds, baking a bundt cake, making molded candies or a Jell-O
mold. In fact, for fun, you could have a snack ready of a jello mold for
the end of the lesson. If you can find a lobster mold, you’d even be
keeping with the theme!
- Scientists think
that life in the ancient seas might have been similar to modern sea life
in many ways. The water would have been salty. There would have been
lots of plant life for animals to feed on. There would have been
animals, but in the ancient times, there were only the kinds of animals
that had no backbones. We call these invertebrates. These animals often
had skeletons on the outside of their bodies, an exoskeleton. We know
about them because of fossilization.Continue your
discussion, painting the picture of an ancient sea habitat. Talk about
the animal species that would have made the seas their home. Compare
them to modern animals that might have similar characteristics. Ask the
students to imagine what would have happened to the animals’ bodies when
they died. As they fell to the sea floor their shells would have become
buried and filled with the soft sand of the ocean bottoms. This is
where we begin to answer the question “How does fossilization take
- BRING OUT THE PREPARED CONTAINER OF PLASTER OF PARIS. This
is a model of the ancient sea floor. It is soft, sandy and powdery. The
only difference is that it isn’t wet. This will be the final resting
place of our shellfish. PLACE THE SHELLS IN THE DRY PLASTER OF PARIS.
- POUR A SMALL AMOUNT OF WATER ONTO THE LAYER OF PLASTER OF PARIS AND SHELLS. Adding
water reminds us that this is a model of the ancient ocean. The ancient
animals’ bodies would be exposed to ocean currents and wave movement on
the sea floor. As the soft body decomposed or became some other
animal’s dinner, the hard shell would fill up with sediments and mineral
- USING THE SIFTER, SIFT A
SMALL AMOUNT OF THE REMAINING PLASTER AND SAND EVENLY OVER THE WATER,
ALLOWING IT TO SINK IN AND COVER THE SHELLS. Sand and other sediments would eventually cover the ancient animals’ bodies.
TO SIFT THE PLASTER UNTIL A SOFT, MUD IS FORMED. (Keep adding the
plaster until all of the water is soaked up. The plaster will now dry
fairly quickly. Plaster of Paris sets up in about 30 minutes.)
process could take a day a week, or even thousands or millions of
years. Over time, the ancient sea might begin to dry up. There are lots
of reasons this could have happened: movements of the earth’s crust,
changes in temperature or volcanic actions could all change the depths
of the ancient waters.
- TAKE A PLASTIC OR RUBBER DINOSAUR AND MAKE AN IMPRINT OF THEIR FOOT PRINTS. As
the water level got lower and lower, muddy swamps and the thick
vegetation they grew made good homes for species that could breathe the
air, reptiles. As they walked or crawled through the swamps, their heavy
bodies made tracks in the soft mud.
is a long slow process. It takes many thousands or millions of years
for a fossil to form. Minerals in the water are left in tiny holes or
pores in the shell or bone. Eventually one molecule at a time the
minerals replace the original materials. What is left is a stone that
looks exactly like the shell or bone that once was.
THE PLASTER TO DRY. You could proceed immediately using a prepared tray
that is already hardened or you could end the lesson here and return to
it when the tray is dry.
Fossilization Lesson Plan Part 2; Fossil Excavation
More fossil lesson plans