Key Concepts. Density is a measure of how heavy something is compared to its size. If an object is more dense than water it will sink when placed in water, and if it is less dense than water it will float.

Is denser lighter or heavier?

Students should realize that if an object weighs more than an equal volume of water, it is more dense and will sink, and if it weighs less than an equal volume of water, it is less dense and will float.

Does density mean light?

Density is the mass of an object divided by its volume; in other words, how much of something has been packed into a certain amount of space. Mass refers to how light or heavy an object is. An object may be very heavy (have a high mass) but have low density because it weighs very little per unit of volume.