Summary

In this activity students will observe the states of matter while making a root beer float. They will also discover the differences between a solid, a liquid and a gas.

Grade Level

Elementary School

Objectives

By the end of this activity, students should be able to:

• Understand what chemical and physical changes occur when ice cream is added to root beer as it relates to the states of matter.
• Identify and describe the physical properties of matter in its various states.
• Distinguish between the states of matter and give examples of each.

Chemistry Topics

This activity supports students’ understanding of

• States of matter
• Physical properties
• Physical change
• Chemical change

Time

Teacher Preparation: 15 minutes

Lesson: 1 hour

Materials

• Root beer (8 cups in each 2 liter bottle)
• Vanilla ice cream (1 gallon=32 scoops)
• 1 cup measuring cups, 1 per group
• Ice cream scoop, 1 per group
• Plastic cups, 1 per student
• Straws, 1 per student

Safety

• Normally, eating materials used in a science investigation is discouraged. You should take great caution if allowing students to eat materials used as part of the activity. Any items that have been in contact with classroom equipment should not be consumed.
• It’s advised that you set aside extra quantities of the edible components instead of eating items directly used in the activity. You should also be sure to check for allergy restrictions among students.
• No other specific safety precautions need to be observed for this activity.

Teacher Notes

• This activity is suitable for Grade levels 1-5
• Depending on student’s age you may want to pre-scoop ice cream into another container.
• Brain pop Jr. has these helpful video to introduce the concepts of physical and chemical changes as well as the states of matter.
  • Video: Physical and Chemical Changes
  • Video: Changing States of Matter
• Introduce lesson: Indicate to students that they will observe 3 states of matter today. Discuss the differences between solids, liquids, and gases. 
  • Review the states of matter by going over the basic information below: Depending on your student’s knowledge and experience, you could teach this as new information or as review.
  • All matter on Earth is made up of extremely tiny particles called atoms and molecules. At normal temperatures, these atoms and molecules are arranged as a solid, liquid, or gas. These three characteristics or “states” of being a solid, liquid, or gas are called the “states of matter”.
    
  • In a solid, molecules are strongly attracted to one another and vibrate but do not move past one another. They stay in fixed positions because of their strong attractions for one another. A solid has a definite volume and a definite shape.
  • In a liquid, molecules are attracted to one another but are able to move past one another. A liquid has a definite volume but does not have a definite shape.
  • In a gas, molecules are not attracted to each other much at all. The molecules in gas move freely past each other. A gas does not have a definite shape of volume. Gas molecules will spread out evenly to fill any container.
• Explain chemical and physical changes. Physical changes can happen when matter changes size, shape, or form. After a substance goes through a chemical change, it becomes a different substance.
• Introduce Vocabulary:
  • Physical change: matter changes size, shape, or form.
  • Chemical change: a substance becomes a different substance.
  • Physical properties: characteristics such as as shape, size, color, and texture used to observe and describe matter.
• Depending on the age of the students, you may want to discuss the pre-lab questions as a class or ask students to complete them independently.
• Procedure:
  • Create an anchor chart with the students after discussing the differences between solids, liquids, and gases. (Draw a melting ice cube and evaporating water and ask them to help you label each state)
  • Have students make a drawing of their cups or give them the student worksheet. Tell them they will be recording their results/labeling and adding things to the picture of the cup as we complete the activity.
  • Before you begin make sure that students remember to pour slowly because of the bubbles that will be created. Also make sure to set up paper towels for accidents-This part can get messy.
  • Have the student’s take turns measuring 1 cup of root beer and pour ½ of it into cup. Discuss what physical properties make the root beer a liquid. Be sure that students discuss the bubbles they see in the root beer. Let them know that when root beer is made at the factory, lots of gas is added to the liquid root beer to make it fizzy. Explain that the added gas is called carbon dioxide. This is the same gas that is added to other sodas to make them fizzy. Have them draw and label the liquid on their picture.
  • Have students discuss what physical properties make the ice cream a solid. Then have them add two scoops of ice cream. Depending on the students age you may want to have extra help with this if possible or pre-scoop the ice cream so that they can just add it to the cup. Have them draw and label the solid on their picture.
  • Have them slowly add more root beer to the cup and observe what happens.
  • Ask students what they noticed when they poured the root beer on the ice cream. (They should have seen a lot of foamy bubbles). Ask students what state of matter the foam is. (Mostly a gas, but the surface of the bubbles is a liquid). Have them draw and label the gas on their picture.
  • What is produced? Is this a physical or chemical change? It is a physical change since the carbon dioxide gas that was in the root beer came out when the root beer was poured on the ice cream. The ice cream has lots of tiny bits of ice where the carbon dioxide molecules stick and gather together to become tiny gas bubbles. The carbon dioxide didn’t become a different gas or other substance it just came out of the root beer.
  • Students can drink their floats while they discuss the activity. Afterwards, have the students write an explanation about what changes occurred and why.
    • Note: Ice cream = solid; Root beer = liquid; Air bubbles = gas