Introduce the unit on states of matter simply. Students need a solid base of information on which they can build with other experiments. They must first understand the primary differences between gases, liquids and solids. Place three beakers on an empty counter or table at the front of the classroom. Place an orange in one beaker and water in another. Leave the third beaker empty to represent air. Ask students what they observe about the objects in each of the three beakers. Call on three fifth-graders to come to the front of the room and have each one stand behind one of the beakers. Ask each student whether the contents of his beaker are solid, liquid or gas. Tell the students to turn over their beakers. Illustrate the differences between the solid object and liquid by defining whether the object holds its shape, spreads to fill a container or surface, or can be held. Describe each state's characteristics, such as transparency. Discuss how the shape of each object changed or stayed the same when the beakers were overturned. Lead a discussion about particles and how solid objects are closely contained, liquids are free-flowing and matter in a gaseous state is hard to contain.
Get fifth-graders into the lab for a hands-on activity to capture the interest of kinesthetic learners. An experiment on mass as it relates to states of matter challenges students to take a technical, scientific approach by weighing objects while thinking about broader concepts relating to objects — water or gas within a solid, for instance — they cannot necessarily see or feel. Separate the class into work groups of two or three students. Give each group an orange, a beaker and a scale. Tell students to weigh both the orange and beaker, recording the measurements on paper. Go around the room and cut the oranges in half for the students. Tell them to juice the oranges into the beakers, capturing all possible liquid. Instruct groups to weigh the beaker with the orange juice and subtract the original weight of the beaker. Tell groups to weigh the squeezed orange halves. Compare the measurements and ask students to give their impressions of whether the numbers add up. Ask them whether the weight of air should be considered. Also ask if other objects can be at once both solid and liquid like the orange — or liquid and gas, like soda pop — and have the groups create a list of those kinds of objects.
A simple test can be applied to water, showing students how temperature can affect the state of matter at various points. This visual activity will quickly reinforce the impact of hot and cold temperatures on an object. It also serves as a springboard for instruction on how the movement and formation of molecules can determine the state of matter. Give students a dish with an ice cube to keep on their desk during class. Ask them to write whether the water you have given them is a solid, liquid or gas. At the front of the class, light a burner and place an ice cube in a heat-resistant clear beaker. Ask students whether temperature will change the state of the ice. When it becomes water, ask students again to predict the outcome as you continue to heat the beaker. Illustrate the changes in the water from solid to gas by drawing molecules on the chalkboard; show closely grouped molecules for solid, linked but longer chains of molecules for liquid, and free atoms for gas. Ask students whether they believe they originally wrote the right answer for water's state of matter for an engaging, class-ending discussion.
Chemical reactions can impact the state of matter, so design a demonstration for students to see, smell or hear changes resulting from molecular interaction. Place baking soda into a clear beaker. Ask students to describe the powder's state and characteristics based on what they have learned. Place a jug of vinegar on the counter and ask students to do the same describing the liquid. Ask them to predict the outcome when the two substances are combined. Pour vinegar into the beaker of baking soda and have students describe the outcome that occurs due to chemical reactivity. The bubbling, physical reaction may intrigue students who otherwise may be struggling to grasp the concept. Mix other combinations, such as milk and vinegar or a bar of soap and water, so students can touch the resulting products and put the three states into perspective.