Grades K-4 National Science Standards - Science as Inquiry: I - Form questions about objects, organisms, and events in the environment - Conduct investigations - Physical Science: II - Objects have many observable properties, including size, weight, shape, color, temperature, and the ability to react with other substances. - Materials can exist in different states--solid, liquid, and gas. Some common materials can be changed from one state to another by heating and cooling. - Light travels in a straight line until it strikes an object. Light can be absorbed by the object. - Heat can be produced in many ways, such as burning, rubbing, or mixing one substance with another. Heat can move from one object to another by conduction.