Sink and Float-Is There A Set Rule?

Today during our collaborative time, we took our experiences with sinking and floating and began to explore ideas of displacement and density, while thinking about variables such as texture, shape and size.  Some of the objects explored today included a rubberband, a nail, coins, wood chips, leaves, plastic cubes, buttons, and bolts. Afterwards, we starting putting some hypothesis' together to understand what we had observed.  Below in the video is SOR and AK trying to determine whether having a hole in the object determines its ability to sink or float.

During a class discussion, one student had mentioned that a marble sank because it was heavier than the water and the air.  KeA responded that "Well, how does a big ferry boat float?  It's heavier than water!"  A question about displacement came up from ZK "What if (the object) stuck in the middle of the water?" He was referring to an object half floating and half sinking. Some misconceptions also popped up, such as: "a boat floats during the day and sinks at night because it can't see", and "an object sinks because it wasn't moving fast enough." We are very excited to see where this exploration leads us as we continue to examine how water is essential to life.  I will also be working with the ideas of controls and variables as we experiment using the scientific method.