Become a Palaeontologist for an Hour

Make fossils with your kids and open the door to conversations about fossils, paleontologists and chemical reactions.

Become a Palaeontologist for an Hour

I have made these dinosaur eggs a few time with Mr almost 3. Safe to say his favourite thing to do lately is hunt for dinosaur bones. A messy sensory activity that opens up the doors to a conversation about fossils, palaeontologist and chemical reactions.

What you will need:

  • Small plastic dinosaurs, fish or other animals. I used small dinosaurs found in the party section of our local $2 shop
  • Bi-carb soda. I used a homebrand  and 1kg made 8 very large eggs
  • Water
  • Food colouring
  • A large mixing bowl
  • Whisk or fork. I used a fork
  • A large tray lined with baking paper
  • Vinegar. I used a homebrand white vinegar.
  • Plastic take away containers.
  • Spoons, plain brushes, plastic eye droppers, plastic cups, spray bottles and/or plastic medicine syringes (like the ones that come with the kids paracetamol) .
The formed eggs
The formed eggs


  1. Place the bi-carb soda in a large mixing bowl.
  2. Add a few drops of food colouring to the bowl and mix, if more colour is desired add some more drops of food colouring
  3. Then, slowly add water and mix.  SLOWLY add more water until the mixture is damp and you can mould it, but not too wet.
  4. Place some of the mixture in your hand, and then lay a toy on top.  Cover the toy with the mixture and form into an egg shape, securing the toy inside
  5. Place the eggs onto a tray lined with baking paper. Leave the eggs to dry over night, I found with the larger eggs they need to be left between 24 – 48 hours. However don’t let them dry in the sun as they will dry too fast and crack
  6. Once they are dry, white vinegar will make the bi-carb fizz and reveal the toy.We have done this as an indoor activity at playgroup by placing the egg into a take away container, pouring the vinegar over the egg, using paint brushes to brush away the fizzing mixture and also using eye droppers and plastic medicine syringes.


We have also done this as an outdoor activity forgoing the take away containers. Mr almost 3 used sticks and rocks to break open the eggs then poured and sprayed vinegar on them.

Full credit for the idea goes to the blog “Growing a Jeweled Rose“.