In this topic, you will learn how to identify objects by describing them.

Matter is anything that has mass and takes up space. Bricks, pencils, and soccer balls all have mass and take up space, so they are all matter.

Some objects take up more space than others. An object that takes up more space has a greater volume. Volume is how much space matter takes up. A refrigerator has a greater volume than a brick.

Another way to describe matter is to describe the matter's mass. Mass is how much matter is in an object. An object with a large mass feels heavy. An object with a small mass feels light. A school bus has more mass than a bike. A bike has more mass than an apple.

You can measure the mass of an object. One unit used to measure mass is the gram. One gram is a small amount of mass. Two paper clips equal about one gram. A nickel is about five grams. You can use the letter g to represent the word gram. You can measure the mass of larger things in kilograms. One kilogram is equal to 1,000 grams. You can represent the word kilogram with the letters kg.

When you describe an object, you are naming its property. A property is a characteristic of something. Some properties are common to all types of objects. For example, all matter has volume and mass. Other properties are special to each type of matter. Size, shape, color, and texture are other properties of matter. Some objects are hard, while others are soft. Some objects float in water, while others sink.

Mass and weight are related. An object with more mass also has greater weight. The weight of an object is the pull of gravity on that object by Earth or any other large body in space. Gravity is the pulling force between two objects. Gravity is much stronger on Earth than on the Moon, because Earth has much more mass than the Moon.