Misconceptions in Science

Most cardboard boxes would start out floating, but the porous nature of the cardboard would allow the water to swamp the voids, changing the density of the overall structure. The cardboard would become waterlogged and sink.A marble would sink because the density of the marble relative to the amount of displaced water would be too great. The surface area of the marble and the surface tension of the water would not create a ratio conducive to buoyancy.An orange is able to float because the orange rind is a low-density material. The makeup of an orange rind provides buoyancy for the orange. It is interesting to note that if an orange is pealed from the rind and placed in a bucket of water, it will not flood because the removal of the orange rind has altered the overall density of the object.One common misconception children have about objects sinking or floating is inked to the weight of the object. Many children think that heavy things sink and light things float. We know that this is not true. The density of the object relative to the density of the water is the determining factor in whether something sinks or floats. A misunderstanding of force also causes this misconception. Students reason that something heavy pushed down on the water harder than something light. If it floats, the water is pushing up hard enough to support it, but if it sinks the water is not strong enough to support it. Students need to understand the water doesn’t push up against the object. The determining factor is the relationship between water density and object density.Another misconception many students have is that small items will float more easily than large items. This is closely related to the idea of weight being a determining factor and shows a misunderstanding of density as well. Many young elementary children do not understand the differences between density and weight. For example,

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