Fossil molds and casts

The resource is an activity that guides you through the process of creating a mold or cast of items of your choice.  There is a small section on background information that describes how fossils are created.  There is not an assessment piece.  This is an activity guide that could be used in conjunction with another lesson or as a culminating activity.  It could also be modified for any age group.  

Standards & Objectives

Academic standards
GLE 0107.5.2
Recognize that some organisms which formerly lived are no longer found on earth.
GLE 0207.5.2
Draw conclusions from fossils about organisms that lived in the past.
GLE 0507.5.2
Analyze fossils to demonstrate the connection between organisms and environments that existed in the past and those that currently exist.
GLE 0807.5.6
Investigate fossils in sedimentary rock layers to gather evidence of changing life forms.
Alignment of this item to academic standards is based on recommendations from content creators, resource curators, and visitors to this website. It is the responsibility of each educator to verify that the materials are appropriate for your content area, aligned to current academic standards, and will be beneficial to your specific students.
Learning objectives: 

Students will be able to:

  • Distinguish between a mold and a cast.
  • List the properties of a mold and a cast.
  • Describe which fossil gives more information about the once living object.

Lesson Variations

Blooms taxonomy level: 
Differentiation suggestions: 

To make tracks, try to get animals that you can let walk or slither across the wet plaster. If you do, make sure the plaster is firm enough for the animal to walk on. Insects are easy to find.

Extension suggestions: 

Have students trade fossils with another student for observation purposes. Describe what you see in the new fossil and what it is or may have done while it was living, i.e.: walking, swimming, meat eating, vegetarian eating, defense, etc.

Helpful Hints

Materials needed:

  • Modeling clay
  • Plaster of Paris
  • 12-16oz. plastic soda pop bottles
  • Small paper cups 6 oz. sized
  • Leaves, plastic dinosaurs or bugs, shells and twigs
  • Water Bucket or bowel to mix plaster in
  • Paper towels
  • tooth picks
  • labels