2 class periods of 15 minutes each
Individual
Students look for examples of chemical and physical changes in the world around them.
For the Teacher:
Physical changes, which do not change the composition of matter, and chemical changes, which do change matter to new kinds of matter, are happening every day in our environment. Physical changes include water evaporating, clothes drying in a dryer, changing the size of food items, chopping wood, erosion, etc. Chemical reactions include fruit rotting, food spoiling, rust, decay of plants, burning wood, silver tarnishing, cooking and baking, etc.
Step 1: Discuss the difference between a physical change and a chemical reaction. Ask: "What are some physical changes that occur in our environment?" List several on the chalkboard. Ask: "What are some chemical reactions that occur in our environment?" List several on the chalkboard.
Step 2. Give the students the "What's Happening in My World" worksheet. [Attached below.] Assign each student to find four physical changes and four chemical reactions that have not been listed on the chalkboard. Discuss how students might find these examples.
Suggestions: Interview parents, observe carefully, look at reference materials, observe someone who works with garbage disposal, interview someone in the food industry.
Step 3. When students return with their information, discuss the importance of physical changes and chemical reactions in our daily lives.
Evaluate the student worksheets for accuracy.
Take the students on a walking quiz. Instruct them to bring paper and pencil. On your walk point things out and ask students to identify them as either physical changes or chemical reactions. Examples could be: