Here's a simple explanation:

* Imagine two balls of clay, both weighing 1 kilogram (kg). This means they have the same mass.

* Now, let's shape one ball into a flat pancake and leave the other as a sphere. The pancake will have a much larger volume than the sphere, even though they both have the same mass (1 kg).

This happens because:

* Density: Density is the amount of mass packed into a given volume. The pancake has lower density because the same amount of clay is spread out over a larger area. The sphere is more dense because the same amount of clay is packed into a smaller space.

Here are some real-world examples:

* A kilogram of feathers and a kilogram of iron: Both have the same mass, but the feathers take up much more space (higher volume) because they are less dense.

* A glass of water and a glass of ice: Ice is less dense than water, which is why it floats. A certain amount of water will occupy less space (have lower volume) when frozen into ice.

In summary: Objects with the same mass can have different volumes because their density can vary. The more dense an object is, the less space it will take up for a given mass.