This lab can let students do "virtual" measurements of the mass and volume (via water displacement) for a variety of objects.You can grab on object by holding the mouse down over it. You can then drag the object to either of your tools: the beaker which measures water displacement (note the sophisticated thumb tack that hold things underwater at the time) and the big scale.
Using the tools you will find the mass and volume of the objects. You can also drop your objects in the pail to see if they sink or float. Then, consider relationships involving the mass and volume to try to predict the sinking or floating.
To test your theory, don't use all the objects right away, save several to test your theory.
Questions to consider:
Does the mass of an object tell you whether or not the object will sink or float?
What about the volume (do bigger objects sink compared to small ones)?