Physical changes are changes in the physical properties of matter. Chemical changes are changes in the chemical properties of matter. Matter cannot be created or destroyed even when it changes. This is the law of conservation of mass.
- MCR.6-8.SCI.8.6, 8; MCR.6-8.SCI.12.7
- NSES.5-8.A.1.4; NSES.5-8.B.1.2
- AAAS.6-8.4.D.12, 17
- Define and give examples of physical changes in matter.
- Define and give examples of chemical changes in matter.
- State the law of conservation of mass.
chemical change: change in matter that occurs when matter changes chemically into an entirely different substance with different chemical properties
law of conservation of mass: law stating that matter cannot be created or destroyed
physical change: change in one or more of matter’s physical properties
Introducing the Lesson
Show students a small wooden toy and ask them to brainstorm ways they could change it (e.g., use a hammer to pound dents in it, cut it into smaller pieces with a saw, burn it in a fire, paint it to change its color, drill holes in it). Tell students they will learn about changes in matter in this lesson.
Demonstrate physical and chemical changes by cutting a sheet of paper and burning an identical sheet of paper. Discuss the products of each change and whether either change is reversible.
Guide students in making Frayer models for the terms physical change and chemical change. You can see a sample Frayer model below. Students should keep their completed models in their science notebook.
Term: physical change Definition: change in one or more of matter’s physical properties.
Drawing: [Student sketch of a saw cutting a log]
Example: Cutting a log
Non-example: Burning a log
Reinforce and Review
Copy and distribute the lesson worksheets in the CK-12 Physical Science for Middle School Workbook. Ask students to complete the worksheets alone or in pairs to reinforce lesson content.
Lesson Review Questions
Have students answer the Review Questions listed at the end of the lesson in the FlexBook® student edition.
Check students’ mastery of the lesson with Lesson 3.3 Quiz in CK-12 Physical Science for Middle School Quizzes and Tests.
Points to Consider
Some physical changes in matter are changes of state.
- What are the states of matter?
- What might cause matter to change state?