Entries in mass (2)
Students have a major misconception that mass determines whether an object floats or sinks. This is an activity that forces students to deal with that misconception and hopefully break it. The following materials are needed:
Have the students read the statement, "Objects that are high in mass, sink in water." Have the students show in some way if they agree with the statement, disagree with the statement, or are somewhat in between. Have them explain why they think that way and give examples. Then present the students with the list of all of the items to be placed into the tank, arranged according to their masses. Do not show the objects to the students. Have them write a hypothesis for each item (on whether they will sink or float) based only the property of mass. Then drop each item one by one, in order of their masses, into the water. Have students record the results. The students will realize that mass has nothing to do with whether an object sinks or floats. Then show the students the objects' densities. Hopefully they see the pattern of those objects with densities less than one float, and those with densities greater than one sink. It is not important to explain what density is at that point, but just that it is a property of matter that is vital in determining if an object floats or sinks.