Investigating Fossils and living organisms

Chris Bakke, Clearbrook-Gonvick Elementary, Clearbrook, MN, created by me - to fit MN standards on Fossils vs living organisms
Author Profile


In this lab, students will observe and compare fossils with living organisms. Students will journal their findings and develop 10 "how", "what", or "where" questions about fossils and living organisms. Students will make their own "fossils" and compare them to the "organism" from which they where made. Further study of fossils can be done from the students' questions.

Learning Goals

This activity is designed with several goals:
- students will compare real fossils to living organisms
- students will make a "fossil" and compare it to a real fossil.
- students will make a "fossil" and compare it to the "organism" it was made from.
- students will journal their observations, procedures, and questions.
Cast Fossil: A cast is formed when an indentation left by a decayed object has been filled with minerals that harden to form a rock the shape of the original object.

Mold Fossils: A mold is formed when there are hollow, complete indentations left by an object that has decayed.

Trace Fossil: A one sided Mold Fossil. Usually these originated from fragile objects such as leaves.

Whole Animal Fossil: A fossil formed when an animal was caught in a soft liquid and covered completely. Example: fossilized insects that were trapped in tree sap are examples of this - amber.

Authigenic preservation - Fossils which are the molds and casts of organisms after they have dissolved or rotted away.

Carbonization (Coalification) - When all of the elements, except carbon, that made up the original organism are removed. For example: all of the hydrogen, nitrogen, and oxygen are removed.

Permineralization (Petrification) - When the original organic tissues are replaced with minerals from the surrounding rock (including calcite, pyrite, or silica).

Unaltered preservation - When an organism is preserved in its original state and is not replaced with minerals. Examples of this include insects which become trapped in tree sap, which later turns to amber.

Recrystalization - When crystals form within the original structure and eventually replace it, the result is a crystallized copy of the original organism.

Context for Use

Grade Levels: 3 - 6
Class Size: Any
Time: Multiple class sessions may be needed to complete this lesson, this depends on teacher options (lesson written for 3 days).
Collaboration: Art instructor and/or a kiln (if making clay molds or casts)
Prior Knowledge:
Preparation: Fossil and Geology Study.
Adaptation to other areas of study:


-Plaster of Paris

-Petroleum Jelly

-Objects for making fossils (leaves, hand, shells...)

-Actual fossils



Subject: Geoscience:Paleontology
Resource Type: Activities:Classroom Activity, Lab Activity
Grade Level: Intermediate (3-5)
Theme: Teach the Earth:Course Topics:Paleontology

Description and Teaching Materials

Day 1:
Materials: Several fossils and corresponding organisms

- Students observe and compare fossils to living organisms. If possible, fossils should "match" some of the "living" organisms that are available for comparison. For example: leaf fossils vs. leaves, shell fossils vs shells...
- Students journal 5 observations or more of these comparisons
o For example: color, weight, size, texture...
- Students develop 5 questions for further study.
- Class shares their observations.
- Teacher notices that someone wants to know how a fossil is made.

Day 2:
Lab -Make "fossils":
Clay, Petroleum Jelly

-Objects for making fossils (leaves, balls, hand, shells...)
-Art Resin (optional) - if you want to do resin, bring in some dead bugs

Students will make, mold, and trace "fossils". Whole animal fossils could be a safety issue and so could be made either by the teacher as a demonstration - or at the teachers discretion - very carefully by each students or student group.

Students make a clay mold, with an object inside, and use a leaf to make a trace fossil. If desired, students or teacher make a resin fossil using a dead bug.

Mold making instructions:
Soften clay in your hands; flatten to a thickness of about 1/2 inch. Grease object lightly with petroleum jelly, then press clay all around it. When entire creature is covered with clay, students need to carefully carve their name or initials into each part of the clay, then using a string, cut the mold in half and gently remove the object from the mold. The two halves of the mold can now be fired or hardened.

Whole Animal Fossils:
To make a Resin Fossil follow the directions for the resin carefully, observing all safety instructions. Pour some of the mixture into a small mold, and after it begins to harden, place a dead insect on the top. Add another layer of resin mix, completely covering the insect and allow it to harden completely. When you remove your fossil from the mold, the insect will last a very long time.

Day 3:
Plaster of Paris or Clay

After Molds and Trace Fossils have been fired in the kiln or hardened, make a cast from each.

Casting a Trace Fossil can be done by softening clay in ones hands and pressing it into the leaf impression (trace fossil that was fired)

Casting a Mold of students creature can be done by putting clay between both sides of the mold and closing the mold, then cutting off excess.

Clay casts can be fired and finished at the teachers discretion.

Teaching Notes and Tips

More information and more ideas:


Successful competion of projects: molds, casts, and trace fossils.

In addition, a quiz could be given over the vocabulary.


5.IV.E.3 The students will compare the structure of fossils to one another and to living organisms.

References and Resources