Recognize that characteristic properties of a substance can be used to identify the substance. Use characteristic properties to separate a substance from a mixture. Distinguish between physical and chemical changes. Recognize that physical changes include freezing, boiling, evaporation, tearing, and crushing. Recognize that chemical changes include burning, rusting of metal, and souring of milk.
Fossil fuels contain stored solar energy and are considered nonrenewable resources.
Observe a generator. Describe how electrical energy can be produced from a variety of energy sources and can be transformed into almost any other form of energy. Describe methods for conserving electricity. Understand that material and energy may be changed in form more than once as interactions occur within a complex system. Heat energy is almost always one of the products of energy transformations.