Sink or Float

We conducted a Sink or Float experiment in class yesterday. Each student brought in something from home that they thought would either sink or float. Some of them were surprised about why some things float and others do not. Bath toys float because they are hollow inside, but if they fill up with water, they will sink! They were all very surprised when a cup was floating at first but as the water filled up inside the cup, it started to sink. Science can be so fun!