Float or Sink?

We looked carefully at our class pumpkin and tried to determine what would happen if we put it in a tub of water.  We each took turns holding it and making our decisions.

Most of us thought that such a heavy object would sink.
We placed the pumpkin in a large tub of water and found that it didn't sink at all.  It floated! It bobbed up and down at the surface, about halfway in and halfway out.

 When we carved it later, we found that it was full of air.