Describe evidence that supports the dual wave - particle nature of light. (recommended)
Energy is a useful conceptual system for explaining how the universe works and accounting for changes in matter. Energy is not a “thing.” Students develop several energy-related ideas: First, they keep track of energy during transfers and transformations, and account for changes using energy conservation. Second, they identify places where energy is apparently lost during a transformation process, but is actually spread around to the environment as thermal energy and therefore not easily recoverable. Third, they identify the means of energy transfers: collisions between particles, or waves.
The dual wave-particle nature of matter and light is the foundation for modern physics. (recommended)