Best examples of modeling fossil formation for students

Hands-on examples of modeling fossil formation to start with

When students ask for an example of a fossil model that actually makes sense, I always start with three simple ideas: a mold-and-cast fossil, a mineral replacement fossil, and a trace fossil. These are easy to build, easy to explain, and they match real examples that paleontologists work with.

Instead of memorizing definitions, you’re going to build them.

Think of these projects as time machines in a tray: you speed up processes that usually take millions of years so they happen in a day or a week, using salt, plaster, clay, gelatin, and other everyday stuff.

Below are some of the best examples of modeling fossil formation that work well for science fairs, classroom demos, or at-home experiments.

Clay mold and plaster cast: the classic example of fossil formation

If you only pick one project, this is the one. It’s one of the clearest examples of modeling fossil formation because it matches how many shell fossils form in sediment.

You press a real shell, plastic dinosaur, or leaf into soft modeling clay. That imprint becomes the mold. When you pour plaster of Paris into that mold and let it harden, you’ve made a cast—a 3D copy of the original object.

This example of a fossil model shows two important ideas:

Sediment can capture the shape of an organism.
Later minerals (your plaster) can fill that shape and harden into rock.

To level this up for a science fair, you can:

Compare smooth vs. detailed objects and see which leaves better fossil models.
Test different clays (air-dry, oil-based, homemade) and document which holds details best.
Add labels explaining that many shell fossils in limestone are real-world examples of mold-and-cast fossils.

If you want to connect this model to real science, the U.S. National Park Service has an accessible overview of fossil types and how they form: https://www.nps.gov/subjects/fossils/index.htm

Salt or sugar crystal “petrified wood”: modeling mineral replacement

Petrified wood is a favorite in rock shops and museums, and it’s also one of the best examples of how minerals can replace organic material cell by cell. You can’t fully copy that at home, but you can model the basic idea using salt or sugar crystals.

Here’s the concept in simple terms:

You use a porous material (a sponge piece, a small stick, or cardboard) to stand in for wood.
You soak it in a hot, saturated solution of salt or sugar.
As water evaporates, crystals grow inside and on the surface.

This becomes one of your best examples of modeling fossil formation by mineral replacement:

The original material (your “wood”) is slowly coated or partly invaded by crystals.
You can cut it open and show how minerals filled spaces in the structure.

To make this project science-fair ready, you might:

Try different solutions: table salt, Epsom salt, sugar, or baking soda.
Track crystal growth over several days with photos.
Explain that in real petrified wood, minerals like quartz replace the original wood tissue over long periods, often in volcanic ash-rich environments. The U.S. Geological Survey has a nice introduction to rocks and minerals you can reference: https://www.usgs.gov/youth-and-education-resources/geology

This is a great example of how you can talk about mineralization without needing millions of years.

Gelatin or agar “amber”: trapping insects in fake tree resin

Amber fossils—those insects perfectly preserved in golden “stone”—are some of the coolest real examples of fossil preservation. To model this, you don’t need real resin; you can use gelatin, agar, or even clear craft glue.

Here’s how this example of fossil modeling usually works:

Make a clear or slightly colored gelatin or agar solution.
Pour a thin layer into a cup or mold and let it start to set.
Add a small plastic insect, leaf, or fake feather.
Pour more gelatin over the top and let it fully harden.

You’ve just created one of the simplest examples of modeling fossil formation by entrapment in resin, similar to amber.

To turn this into a more advanced project:

Make several “amber” samples and test how well details are visible through different thicknesses.
Compare gelatin, agar, and clear glue for clarity and durability.
Add a section to your display explaining that real amber is fossilized tree resin, and that scientists have studied amber fossils to learn about ancient ecosystems. The Smithsonian’s National Museum of Natural History has good background reading on fossils and deep time: https://naturalhistory.si.edu/education/teaching-resources/earth-history

This model is especially good for younger students, because it’s visual, simple, and feels a bit like making candy—without the eating.

Footprints in sand and plaster: modeling trace fossils

Not all fossils are bones. Some of the best examples of fossil evidence are trace fossils: footprints, burrows, nests, and even coprolites (fossilized poop). For a model, footprints are the easiest and most dramatic.

Here’s how this example of modeling fossil formation plays out:

Fill a shallow tray with damp sand or fine dirt.
Press in toy dinosaur feet, your own fingers, or shoe soles.
Gently mist with water, then pour a thin layer of plaster of Paris over the surface.
Once it hardens, you peel off a solid “rock” with preserved tracks.

This becomes one of your clearest examples of how behavior can be recorded in the geologic record.

To push this into science-fair territory, you can:

Compare different sand dampness levels to see which preserve the best tracks.
Measure stride lengths and talk about how paleontologists estimate speed and size from real dinosaur tracks.
Show photos of famous track sites, like those in Texas and Colorado, to connect your model to real examples.

Trace fossils are often underused in projects, but they’re powerful examples of modeling fossil formation that go beyond “just bones.”

Layered sediment cups: modeling burial and time

Many students focus only on the fossil itself and skip the burial process, but layering is where a lot of the science lives. A simple sediment cup can show how organisms get buried and preserved.

In this example of a fossil model:

You use a clear plastic cup as your “time column.”
Add a small shell, leaf, or plastic bone.
Sprinkle a thin layer of sand over it.
Add a different color of sand or soil, then another small object.
Repeat with several layers, maybe adding a “volcanic ash” layer made from gray craft sand.

When you’re done, you have a vertical stack of “geologic layers” with objects buried at different depths. This is one of the best examples of modeling fossil formation in context:

It shows that fossils form in sedimentary layers, not just randomly in rock.
It lets you talk about relative age: deeper layers are usually older.

You can even gently slice the cup or shine a flashlight through to “discover” fossils like a geologist reading rock strata.

To connect this to real science, you could reference basic stratigraphy concepts from university geology departments, such as introductory materials from places like the University of California Museum of Paleontology: https://ucmp.berkeley.edu

Decomposition vs. preservation: why everything doesn’t fossilize

One of the most powerful examples of modeling fossil formation doesn’t create a fossil at all. Instead, it shows why fossils are rare.

In this example:

Set up two or three containers with similar organic items: leaves, small flowers, or pieces of raw pasta shaped like shells.
In one container, you bury the item in damp sand and seal it.
In another, you leave the item in open air.
In a third, you place it in water.

Over days or weeks, you check what happens. The open-air sample decays or dries out. The water sample may rot or grow mold. The buried sample often stays more recognizable.

This experiment becomes one of your best examples of the conditions needed for fossilization:

Rapid burial can protect remains from scavengers and oxygen.
Exposure usually leads to decay and loss.

You don’t get a real fossil, but you get an example of why only a tiny fraction of organisms ever become fossils. That’s a powerful story to tell on a science fair board.

Using real examples to inspire better fossil models

When students look for examples of modeling fossil formation, they sometimes forget to connect their models to real-world data. Judges love when you show you’ve done that extra step.

Here are some ideas for tying your examples to actual fossils:

Mold and cast model: Compare your plaster cast of a shell to photos of real shell fossils in limestone or sandstone. Explain that in nature, the original shell might dissolve, leaving a mold that later fills with minerals.
Petrified wood model: Show images of petrified logs from places like Petrified Forest National Park and explain that your salt-crystal wood is a faster, simplified example of mineral replacement.
Amber model: Talk about how scientists have studied amber fossils to understand ancient insects, spiders, and even bits of dinosaur-era plants.
Trace fossil model: Compare your plaster tracks to dinosaur trackways documented by geologists. Explain how track depth, spacing, and size help reconstruct animal behavior.

When you use these real examples, you turn a simple craft project into a science investigation.

If you want to go deeper into fossil science, the U.S. Geological Survey offers student-friendly resources on fossils and Earth history: https://www.usgs.gov

Tips for choosing the best examples of modeling fossil formation for your project

With so many options, how do you pick the best examples of modeling fossil formation for your grade level and time limit?

Here’s a simple way to think about it:

Younger students (grades 3–5) often do well with the mold-and-cast clay model, the gelatin “amber,” or the footprint trace fossils. These are visual, quick, and forgiving.
Middle school students (grades 6–8) can combine two or three examples—maybe a sediment cup plus a mold-and-cast fossil and a set of trace fossil footprints—to show different fossil types.
High school students can turn these examples into real experiments: testing which sediments preserve details best, which solutions grow the strongest “petrified” crystals, or how burial conditions affect decomposition.

For a standout science fair display, try to:

Include at least two different fossil types in your models.
Show before and after photos so judges see the process.
Use short, clear labels that explain how each model connects to real-world examples.

Remember, these are models, not perfect replicas. Your job is to explain what the model gets right, what it simplifies, and how it helps us understand the real fossilization process.

FAQ: Common questions about examples of modeling fossil formation

Q: What are the best examples of modeling fossil formation for a quick classroom activity?
For short class periods, the clay mold and plaster cast, footprint trace fossils in sand and plaster, and layered sediment cups are the best examples. They set up quickly, show clear results, and are easy for students to explain.

Q: Can you give an example of a fossil model that shows both burial and fossilization?
A layered sediment cup works well for this. You bury shells or small objects in different layers of sand and soil, then add a mold-and-cast model at one layer to represent where fossilization might occur. This gives you one connected example of how organisms are buried and later preserved as fossils.

Q: How do I make my examples of fossil models look more scientific and less like crafts?
Label everything. Use short captions to explain what each part of the model stands for in nature. Include real fossil photos or diagrams from reliable sources, and write a short paragraph about how your example of modeling fossil formation compares to real processes.

Q: Are there real examples that match these classroom fossil models?
Yes. Mold-and-cast fossils match many shell fossils, mineral replacement models echo petrified wood and some bone fossils, amber models match insect fossils in real amber, and footprint models match dinosaur trackways. These real examples help you show that your projects are simplified versions of actual geologic processes.

Q: Can I turn these examples of modeling fossil formation into a controlled experiment?
Absolutely. You can compare different sediments, different mineral solutions, or different burial conditions and measure which ones preserve the most detail or grow the most crystals. As long as you change one main variable at a time and record your results, your examples of fossil models become real experiments instead of just demonstrations.

Real-world examples of modeling fossil formation for science projects