As students develop an understanding of how long ago dinosaurs roamed the earth, they will develop an appreciation of the ways in which information can be gathered from fossils. Fossils not only tell what prehistoric animals looked like, but as different kinds of fossils are dated together chronologically, a picture of habitats can be reconstructed so that scientists and historians make educated guesses about evolution and the past.
Students will be asked to develop the skill of creating a clay impression. They will learn about how to make a plaster cast from their negative shape. In that way students will develop an appreciation for how fossils help modern generations learn about and value the Earth's past.
Fossil Project Aims and Objectives
During this activity students will
- create their own fossil using clay and an object of their choice
- make a cast of a fossil using Plaster of Paris
- learn about burnishing plaster with boot polish
- present the fossil to the class with an explanation
Fossil Lesson Materials
- objects to imprint in the clay such as shells, rocks, twigs or leaves
- small plug of clay
- sufficient Plaster of Paris for each student to make a cast of their clay impression
- egg rings
- buckets and containers with wooden spoons to mix the plaster
- boxes to sit the clay impression in when casting
- real sample fossils if at all possible
Negative Shape Impression in Clay
Students will examine samples of fossils. Students will be asked to discuss how they think the fossils were made and how they can be used as keys to unlock the Earth’s history.
Student will each
- be given a ball of clay, which they will roll to about the thickness of their egg ring
- press the egg ring into the clay like a cookie cutter
- leave the egg ring in place during the process
- press the object into the clay
- carefully remove the object and an imprint will remain
Process for Taking a Cast of a Negative Impression
- make the plaster casts by placing the clay inside the shoe boxes
- ladle Plaster of Paris onto the impression to make a stamp thick enough to be held in a child's hand
- when the plaster is dry, separate the clay and the plaster gently revealing the fossil
- after 24 hours, burnish the Plaster of Paris cast with shoe polish creating a realistic fossil like effect (see images below)
Integration of Dinosaur Theme
This project can be used as a lead into integrated units of work about dinosaurs or other related topics. Science teachers can introduce a topic about scientific discovery through relics. History teachers can talk about different time spans in the prehistoric world. Art teachers can introduce a unit, which integrates drawing, painting sculpture and design. Other genre could be introduced such as leaf printing and rubbing.
Presenting of the Fossil Project
An archaeological "dig" could be arranged by burying the fossils in the sandpit. Students might be asked to hypothesize an explanation of their find.
Teacher Resources from John Day Fossil Beds website.
Teacher Resources from Queensland Museum: Jigsaw Created by Students from Bentley Park College.