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Time for a tasty geological treat! Grab some ingredients and make some fossil biscuits.

Safety: This activity uses an oven. Ask an adult to help. When working with food, use clean hands and clean equipment.

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You will need

Equipment

• Detergent
• Oven
• Oven mitts
• Baking trays
• Measuring cups and spoons
• 2 mixing bowls
• Mixing spoon
• Fork
• Rolling pin
• Cookie cutters, or a glass
• Toy prehistoric animals – we’re using dinosaurs, but you could also use shells, bugs, or any creature you might find in a fossil!

Ingredients

• 1 cup caster sugar
• 1 cup soft butter
• 1 egg
• 1 teaspoon vanilla essence
• 2 teaspoons baking powder
• 3 cups plain flour
• Extra flour for dusting
• Coloured icing (optional)

What to do

1. Clean your toys in the sink with washing up detergent, and rinse well.
2. Wash your hands.
3. Preheat your oven to 180 °C.
4. Put a cup of butter and a cup of sugar in a bowl. Use a fork or your hands to mix these together.
5. Add the egg and a teaspoon of vanilla to the butter and sugar and mix well.
6. In a different bowl, measure out 3 cups of flour and 2 teaspoons of baking powder and stir well.
7. Add the flour mixture to the butter mixture in batches. Stir to mix between each batch.
8. When everything is mixed together, the dough will be crumbly, but it should come together if you squeeze it. If it doesn’t stick together, try adding a teaspoon of water to the mixture.
9. Spread some extra flour onto a benchtop. Spread some flour onto your baking trays too.
10. Take about half the mixture and put it on the benchtop. Roll it out using a rolling pin until it’s about 5–6 millimetres thick, and then cut out biscuits with your cookie cutters or by using the mouth of a glass.
11. Any extra dough that you cut away can be put back into the bowl to make more biscuits.
12. Make an impression in each biscuit with your toys. We made dinosaur footprints!
13. Transfer the biscuits onto the floured baking tray.
14. Take more dough, roll it out and make more biscuits until you’ve used all the dough up.
15. Ask an adult to put on the oven mitts and put the biscuits into the oven.
16. Bake the biscuits for 8–10 minutes.
17. Ask an adult to take the biscuits out of the oven using oven mitts.
18. Leave the biscuits on the tray to cool for at least 15 minutes before touching them.
19. For extra flair, you can fill the imprints of your fossil biscuits with icing!

What’s happening?

In this activity you’re making a model of a fossil. Animals, plants, and even microorganisms can leave behind fossils.

Traces of life can also be preserved as fossils. These traces can include footprints, shed skins and even poo! (Please don’t try to make a poo fossil biscuit!)

Commonly, fossils are formed when a creature dies in or near water. Their bodies decompose, leaving bones or shells. Water can wash mud or sand over these remains.

As sand and mud turn to stone over time, the bones themselves can do many different things. Sometimes the bones turn to stone. Other times the bones dissolve and disappear, leaving a hole. Other rocks can form inside the hole, making a cast. This is a bit like what happens if you fill the holes in your fossil biscuits with icing.

This common example misses a whole lot of other fossils. Remains can be preserved in volcanic ash, amber (tree resin), and in ice. And these are just a few examples. If you’re keen to know more about fossils, there’s plenty more to research!

Real-life science

How many toes does a dinosaur have? The answer depends on the dinosaur.

Dinosaurs that walked on two feet tended to have three forward facing toes on each foot. But they didn’t always walk on all three toes. Velociraptor, for example, walked on two toes, while the third had a huge claw for fighting.

Triceratops had four toes on their back legs. On the front, they had five, but they only walked on the first three.

Sauropods, such as Brontosaurus, tended to have three claws on the back legs. Their front legs were like pillars, often with a single claw. These front limbs formed horseshoe-shaped footprints!

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