Types of Fossils: A Simple STEM Lesson from Elemental Science

In this simple STEM lesson, you will find the tools you  need to share about the different types of fossils with your students!

Scientists categorize fossils into three main groups -  impression fossils, trace fossils, and replacement fossils. Amber is also often looked at as the fourth type of fossil but, even though a chunk of amber can contain insects that were trapped in resin long ago, technically it is still categorized as a gemstone.

Let's dig into the three main types of fossils, uncover what they are, and get our hands dirty with an activity!

Your Simple STEM Lesson on Fossils

A Brief Explanation of the 3 Types of Fossils 

Fossils are bits of plants and animals preserved from the past. They are several different kinds of fossils based on how they are formed.

Here are the three most common:

1. Impressions fossils

These fossils contain prints, or impressions, of plants or animals from long ago. The plant or animal lands in mud, silt, or sand and makes an impression.

Over time, it disappears, but the impression remains. The mud, silt, or sand hardens into rock, and an impression fossil remains.

2. Trace fossils

These types of fossils capture the activities of ancient animals. These animals leave their footprints or scat, which makes an impression in the soft mud, silt, or sand.

Just like impression fossils, the soil hardens to form rock, preserving a trace of the animal.

3. Replacement fossils

These fossils are replicas of things that were once alive, such as trees or sea creatures. These living things are trapped, die, and are covered by mineral-rich water.

As they rot, the organic parts are replaced by a hard mineral called silica. The minerals fill in the spaces and create a replacement, or replica, fossil of the living thing.

3 Simple STEM Fossil Activities

Simple Fossil Observation

To learn more about fossils, have the students do a simple fossil observation.

For this science activity, you will need:

• A fossil
• A magnifying glass
• A notebook or piece of paper

Have the students examine the fossil using their eyes, fingers, and the magnifying glass. As they observe, ask them the following questions:

• What type of fossil do you have?
• Is your fossil from a plant or animal?
• What similarities are there to something you would find today?
• What differences are there to something you would find today?

Once they are done their observations, have the students write down several things that they learned about the living thing it preserved and sketch what they see. 

2 More Fossil Activities

After they have observed the fossil sample, you can have the students make their own fossil.

Check out the following two articles for ideas:

• Replacement fossils - Have the students make their own replica of a replacement fossil, just like petrified wood, using the linked activity from the Utah Education Network.
• Impression fossils - Have the students make their own impression fossil using a shell or plant from your home with the directions found in the linked article from the Crafty Classroom.

Digging Deeper Into Fossils

A little fun fact that you may not know - every state has its own fossil!

Have the students research and learn about their state’s fossil. You can use these two websites below to help you get started:

• State Symbols USA
• List of US State Fossils from Wikipedia

You can also check out the following books for more information on fossils:

• Digging Up Dinosaurs (Let’s-Read-and-Find... Science 2) by Aliki
• Archaeologists Dig for Clues (Let’s-Read-and-Find... Science 2) by Kate Duke
• Learning from Fossils (Exploring Earth’s Resources) by Sharon Katz Cooper

Wrapping Up Your Simple STEM Lesson

Impression, trace, and replacement fossils are the three main categories of fossils. Your students can learn so much about these preservation pieces by observing and recreating the fossils!

I trust that you and your students will enjoy this simple STEM lesson the three main types of fossils. If you want to learn more, check out our earth science programs:

• Earth Science & Astronomy for the Grammar Stage
• Earth Science & Astronomy for the Logic Stage
• The Sassafras Science Adventures Volume 5: Geology
• Lapbooking through Rocks and Fossils