1.) Tell students that today we will look at everyday uses of products that are made by physical and chemical changes. We will also prepare a dessert that is made using physical and chemical changes. Project the web article attached. Girls will particularly enjoy seeing the history of makeup along with a description of the chemicals used in the process.
(Science News for Kids-Makeup Science
)This website provides a history of cosmetics. The chemical and physical characteristics of makeup are also addressed.
2.) Ask the students to observe the ingredients list on the cosmetics packaging. Allow them to speculate as to the reason behind some of the ingredients. Anticipate answers such as coloring, preservatives, and moisturizers.
3.)Ask students for examples of physical and chemical changes. These terms should have been defined in a previous lesson. In the process of the discussion, be sure to bring in that physical changes can be reversed and chemical changes are irreversible.
4.) Ask for examples of physical and chemical changes that occur in schools. Students may mention exercising in PE or cooking in the lunchroom. This might be a good time to discuss the concept that while many of the changes in food are chemical in nature, some changes are physical. An example would be cutting up lettuce for a salad. If heat is involved, the change is chemical.
5.) Tell the students that today we will utilize both physical and chemical changes to prepare a mixture. Explain to the students that their makeup ingredients respresent a mixture. Ask students for a definition of a mixture. A mixture consists of two or more substances mixed together without chemical bonding taking place.
6.) Ask students to list in their journal examples of physical and chemical change.
7.) Begin to prepare your mixture by opening an unheated can of sweetened condensed milk. Open the room temperature can of heated milk and allow the students to compare and contrast the chemical change that has occurred in the heated can of milk. The heated milk should be thicker and brown. You have made caramel.
8.)Pour the caramel into a bowl. You may want to bring in the term viscosity at this point. If the term has not been addressed by this point, you may introduce it by asking students for differences in physical characteristics between the "uncooked" milk and the "cooked" milk. Students should notice that the "cooked" milk is thicker or more viscous. Viscosity is the resistance of a liquid to flow.
9.)Add 1/2 (approximately) of a cup of smooth peanut butter to the caramel. Have a student stir with a spoon. State that we are now creating a mixture and causing a physical change.
10.)Add one container of Cool Whip (or like product). Have the student stir again.
11.)Add 1/2 cup of chocolate chips and continue stirring.
12.)Have other students place muffin cups on a flat surface and place one vanilla wafer in the bottom of each. Place a spoonful of your mixture in each muffin cup. Serve to each student along with a plastic spoon.
13.)Review the terms physical change, chemical change, mixture, and viscosity as the kids eat their dessert. Be sure to write the recipe on the board so students may prepare their science lesson for family members.