Ingredients
- Baking soda
- Vinegar
- Silicone molds or ice cube tray
- Small surprises (toys, coins)
- Food coloring (optional)
- Mixing bowl
Instructions
- Combine the baking soda and optional coloring.
- Put baking soda in a mixing bowl. If you want colored rocks, add food coloring and stir it through the baking soda before adding vinegar.
- Add the vinegar slowly.
- Pour in a small amount of vinegar at a time while stirring. The mixture will fizz. Pause as needed to let the bubbling settle enough for you to see its texture, then continue adding vinegar gradually.
- Stop when the mixture has turned into a thick paste that can be pressed into a shape.
- Place a surprise in each mold.
- Press one small surprise into each mold cavity.
- Pack the mixture over the surprises.
- Spoon or press the baking soda paste into each mold, covering the surprise completely. Pack it down firmly so the mixture holds together around the object.
- Let the rocks dry.
- Leave the filled molds undisturbed for several hours or overnight.
- Remove the dry rocks from the molds.
- Once they are dry, gently release them from the molds.
- Set up the treasure hunt.
- Hide the finished rocks in a suitable play area and let participants find them.
Notes
Choose surprises that fit fully inside the mold cavities and can be safely handled by the intended participants. Supervise children around small objects.
