This page provides information to support educators and families in teaching K-3 students about solids, liquids, and gases. It is designed to complement the Solids, Liquids, and Gases topic page on BrainPOP Jr.

Matter is all around us. It makes up all things. Scientists classify matter into three main states: solids, liquids, and gases. There are other states, like plasma, but they are mostly beyond the scope of K-3 education. Under certain conditions, matter can change between different states. We recommend watching the Changing States of Matter movie together as a review.

A solid is a kind of matter that has its own shape and does not flow at a given temperature. The molecules that make up a solid are close together and have confined movement. Solids include tables, shirts, glass cups, and clay. A property is a trait or characteristic of matter. Solids can be different colors and textures and have different degrees of malleability. It is important for young children to be able to articulate the properties of an object, as well as classify objects by their properties. Mass is the amount of matter in an object. Students may believe that mass is the same as weight, but this is incorrect. Weight is based on the gravity’s pull on an object. Thus, the weight of an object on Earth is different from weight of the same object on the moon. Mass, however, does not change and is independent of gravity.

A liquid is a kind of matter that does not have its own shape and flows at a given temperature. Liquids take the shape of their containers. The molecules that make up a liquid are farther apart than solids and are able to vibrate and move more freely. Liquids include water, blood, milk, and juice. Liquids can vary in color and viscosity, or thickness.

Like a liquid, a gas flows and does not have its own shape at a given temperature. Gases can take the shape of their containers. The molecules that make up a gas are much farther apart than solids and liquids, and can move independently. Without a container, gases can spread freely. Though you cannot always see gases, they surround us. Air is a mixture of different gases. The sun is also made up of gases. Volume is the amount of space matter takes up. Tools such as measuring cups and spoons can measure liquid volumes. The volume of a gas can be measured using specific formulas. The Sun is made of different gases and plasma. Plasma is an ionized gas, or a gas that is sensitive to magnetism.

Encourage your children to explore their surroundings and find examples of solids, liquids, and gases. How are they alike? How are they different? How do they use solids, liquids, and gases everyday?