Teachers Network


Lesson 1- What are fossils?


1.  What is a fossil?

2,  How are fossils formed?

3.  What is some vocabulary associated with fossils?

Motivation:  Show students pictures of the following fossils.  1 and 2 were taken from http://thinkquest.org/library/site_sum.html?tname=J002507&url=J002507

The other pictures were found in a Google image search on fossils.

Ask leading questions such as:

1.  What are these pictures of?

2.  Are these all the same type of fossils?

3.  Which fossil is in amber?

4.  Which fossil shows a plant?

5.  Which fossils show marine life?


1.  Students are to go to the following sites to research facts for the database below.   http://enchantedlearning.com/subjects/dinosaur/dinofossils and http://web.ukonline.co.uk/conker/fossils/  Click here for a blank student question database.



1.  What is a fossil? Fossils are the remains of ancient animals and plants, the traces or impressions of living things from past geologic ages, or the traces of their activities
2.  How are fossils of hard mineral parts (like teeth and bone) formed?
  • Some animals were quickly buried after their death (by sinking in mud, being buried in a sand storm, etc.).
  • Over time, more and more sediment covered the remains.
  • The parts of the animals that didn't rot (usually the harder parts likes bones and teeth) were encased in the newly-formed sediment.
  • In the right circumstances (no scavengers, quick burial, not much weathering), parts of the animal turned into fossils over time.
  • After a long time, the chemicals in the buried animals' bodies underwent a series of changes. As the bone slowly decayed, water infused with minerals seeped into the bone and replaced the chemicals in the bone with rock-like minerals. The process of fossilization involves the dissolving and replacement of the original minerals in the object with other minerals (and/or permineralization, the filling up of spaces in fossils with minerals, and/or recrystallization in which a mineral crystal changes its form).
  • This process results in a heavy, rock-like copy of the original object - a fossil. The fossil has the same shape as the original object, but is chemically more like a rock! Some of the original hydroxy-apatite (a major bone constituent) remains, although it is saturated with silica (rock).

3.  Where are most fossils found? Most fossils are found in sedimentary rocks - rocks which were created when shells or small loose bits of rock were laid down in layers. Examples of sedimentary rocks are limestone, sandstone, clay and chalk.

2.  Have students log onto http://discoveringfossils.co.uk/fossildictionary.htm and fill in the following database with the definitions.  Click here for a blank student database.



amber A resin produced by certain trees since the Jurassic period.  When secreted from the bark, resin forms a sticky orange fluid which insects and small creatures can become trapped in.  Over time the resin hardens to form Amber, thus preserving itself and any insect or creature within.
ammonite Probably the most commonly associated fossil in the world.  Ammonites are an extinct group of marine 'cephalopod molluscs' that thrived during the Jurassic and Cretaceous period (170 - 65 million years ago).  Ammonites consisted of a coiled shell within which the creature lived.

The period following the Pre-Cambrian, where most marine invertebrates evolved 545 million years ago.  Most organisms before this period were not preserved in the fossil record.


cretaceous A period of time stretching from 142 - 65 million years ago.  The end of this period (the KT boundary) was marked by the mass extinction of the dinosaurs.
dinosaurs The general name given to describe the land-dwelling reptiles which lived between during the Triassic, Jurassic and Cretaceous period (248 - 65 million years ago).
extinction The resulting term given to mark the end of a species or group of creatures.  Extinction usually results from a long-term change in the environment, which subsequently triggers a period of decline and eventual end.

The name given to the remains of trace of creatures or plants which once existed.  A fossil is a rock-like copy of the original object, resulting from the replacement of minerals with those of the surrounding rock.



The period of time extending from 206 to 142 million years ago.  During this time, the Dinosaurs evolved to become the most powerful and diverse group of creatures to have lived on Earth to that time.


The period of time, marked with the great expansion of life in the sea and on the land.  The era stretched from 248 to 65 million years ago, and included the evolution and demise of the dinosaurs.

paleontology The scientific study of fossils, their formation and preservation; the formulation of theories and the history and evolution of ancient life that fossils represent.

The name given to a group of giant flying reptiles which lived between the Late Triassic and Cretaceous periods.

trace fossil

Evidence of former life preserved as a mark on a rock.  A good example would be dinosaur footprints. 


A period of time stretching from 248 to 206 million years ago.  During this time the first dinosaurs began to evolve, which later dominated the earth during the Jurassic and Cretaceous periods.

trilobites A former group of marine arthropods which were characterized by a hard exoskeleton and threefold division of the body


1.  Fossil Hunt- Children can go on a fossil hunt in the classroom.  Fill a shoebox with sand, dirt, and gravel.  Hide some "fossils" in the box.  As each one is found, children should list the date, the place, and what the fossil is on an index card.  This gives children experience in fossil hunting and describing a fossil.

2.  Fossil Jigsaw Puzzle-   Students can go to http://www2.trafford.com/clientimages/Dinomike_StudyGuide.pdf and print a jigsaw puzzle of a fossil.  Then they can cut out the pieces and put the fossil back together!

3.  Fossil Description- Children can log onto http://usoe.k12.ut.us/curr/science/core/4th/4thSciber/fossils/html/intro.htm and do the field study of the fossil in the picture as shown below".

Look closely at the photograph on the left. This "rock" was found by a student  in Utah. Do you see fossils inside the rock? Write a paragraph describing what the fossils in this rock look like.


4.  Have students log onto http://usoe.k12.ut.us/curr/science/core/4th/4thSciber/fossils/html/whatKind.htm and learn in which kind of rock a fossil can be found.  This is an interactive question and answer site.

Follow Up:  This lesson will lead to lesson 2- What are the different kinds of fossils?

Use the following links to navigate through FOSSILS!