Objects that are less dense than water will float, while objects that are denser than water will sink.
Objects that are less dense than water will float. For example, wood is less dense than water and will float on its surface. On the other hand, objects that are denser than water will sink. For example, metals are denser than water and will sink in it.
To determine if an object will float or sink, we need to compare its density to that of water. The density of an object is its mass divided by its volume. If the object's density is less than the density of water (1 g/cm³), it will float. If its density is greater, it will sink.
In the case of the objects Ellen is testing, we need to know their densities. Once we have that information, we can compare them to the density of water (1 g/cm³) to determine if they will float or sink.