I needed to come up with a fossil related activity for kids when I happened upon a set of sand pit moulds of a T-rex, I I also had a ply board with lots of de-lamination... which looked a lot like sedimentary rock formations.
What was needed was something to put into the moulds that looked like stone.... that would be concrete then!
Step 1: Base Board
After laying the body parts out and drawing around them I cut the base into manageable pieces.
I filled any big cracks and made the wood look as much like rock as I could.
Step 2: Casting in Concrete
I mixed the cement, sand and water with some PVA glue to toughen it up a bit.
Wood screws were driven into the base board and joined up with wire to hold the concrete in place, the moulds were packed hard with the mix, pressed into place and the moulds removed.
Step 3: Fossil Jigsaw Ready to Go!
Once it was all dry I sealed the surface of the concrete with more PVA and then off it went to my work place to be used.
I was quite surprised at how long it took the kids to assemble it, it was very much a hit!