Plasticity of the earth's mantle

On Friday 5/22 we did a lab that would give us an idea about the plasticity of the mantle. We mixed water with corn starch and mixed. We then put the mix in our hands. When i rubbed the mix together, it would turn into rock, but when I let it go, it would melt and feel like rubber. Eventhough when the mix melted it was still somewhat hard. When I put my finger in fast, it would go through, but when I put my finger in slowly, the mix would melt when my finger is inside causing it to harden on my fingers a little. In conclusion, this lab gave me an idea of how the mantle functions and how the mantle keeps the crust floating and keeps it from collapsing on itself.