How does density affect sinking and floating in water?

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.

Density is a characteristic property of a substance and doesn’t depend on the amount of substance.

Explanation:

If you compared the weight of wood and an equal amount, or volume, of water the sample of wood would weigh less than the sample of water. This means that wood is less dense than water. Since wood is less dense than water, wood floats in water, no matter how big or small the piece of wood is.

A student might want to know why a boat made out of steel can float when steel is more dense than water. This is not an easy question and requires a different approach than what students have seen so far. We do not necessarily recommend the following explanation for 5th graders but here is the idea:

An object floats when it displaces a volume of water that has a mass equal to the mass of the object. So if a material like steel is shaped into a boat and made larger and larger, it will displace more and more water. When it is large enough to displace a volume of water that has a mass equal to the mass of the boat, the boat will float.

where's the diagram?